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PYSEC-2026-248
Vulnerability from pysec - Published: 2026-06-22 18:16 - Updated: 2026-06-27 10:29Starlette is a lightweight ASGI framework/toolkit. Prior to 1.3.0, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host. This vulnerability is fixed in 1.3.0.
| Name | purl | starlette | pkg:pypi/starlette |
|---|
{
"affected": [
{
"ecosystem_specific": {},
"package": {
"ecosystem": "PyPI",
"name": "starlette",
"purl": "pkg:pypi/starlette"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.3.0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.1.0",
"0.1.1",
"0.1.10",
"0.1.11",
"0.1.12",
"0.1.13",
"0.1.14",
"0.1.15",
"0.1.16",
"0.1.17",
"0.1.2",
"0.1.3",
"0.1.4",
"0.1.5",
"0.1.6",
"0.1.7",
"0.1.8",
"0.1.9",
"0.10.0",
"0.10.1",
"0.10.2",
"0.10.3",
"0.10.4",
"0.10.5",
"0.10.6",
"0.10.7",
"0.11.0",
"0.11.1",
"0.11.2",
"0.11.3",
"0.11.4",
"0.12.0",
"0.12.0b1",
"0.12.0b2",
"0.12.0b3",
"0.12.1",
"0.12.10",
"0.12.11",
"0.12.12",
"0.12.13",
"0.12.2",
"0.12.3",
"0.12.4",
"0.12.5",
"0.12.6",
"0.12.7",
"0.12.8",
"0.12.9",
"0.13.0",
"0.13.1",
"0.13.2",
"0.13.3",
"0.13.4",
"0.13.5",
"0.13.6",
"0.13.7",
"0.13.8",
"0.14.0",
"0.14.1",
"0.14.2",
"0.15.0",
"0.16.0",
"0.17.0",
"0.17.1",
"0.18.0",
"0.19.0",
"0.19.1",
"0.2.0",
"0.2.1",
"0.2.2",
"0.2.3",
"0.20.0",
"0.20.1",
"0.20.2",
"0.20.3",
"0.20.4",
"0.21.0",
"0.22.0",
"0.23.0",
"0.23.1",
"0.24.0",
"0.25.0",
"0.26.0",
"0.26.0.post1",
"0.26.1",
"0.27.0",
"0.28.0",
"0.29.0",
"0.3.0",
"0.3.1",
"0.3.2",
"0.3.3",
"0.3.4",
"0.3.5",
"0.3.6",
"0.3.7",
"0.30.0",
"0.31.0",
"0.31.1",
"0.32.0",
"0.32.0.post1",
"0.33.0",
"0.34.0",
"0.35.0",
"0.35.1",
"0.36.0",
"0.36.1",
"0.36.2",
"0.36.3",
"0.37.0",
"0.37.1",
"0.37.2",
"0.38.0",
"0.38.1",
"0.38.2",
"0.38.3",
"0.38.4",
"0.38.5",
"0.38.6",
"0.39.0",
"0.39.1",
"0.39.2",
"0.4.0",
"0.4.1",
"0.4.2",
"0.40.0",
"0.41.0",
"0.41.1",
"0.41.2",
"0.41.3",
"0.42.0",
"0.43.0",
"0.44.0",
"0.45.0",
"0.45.1",
"0.45.2",
"0.45.3",
"0.46.0",
"0.46.1",
"0.46.2",
"0.47.0",
"0.47.1",
"0.47.2",
"0.47.3",
"0.48.0",
"0.49.0",
"0.49.1",
"0.49.2",
"0.49.3",
"0.5.0",
"0.5.1",
"0.5.2",
"0.5.3",
"0.5.4",
"0.5.5",
"0.50.0",
"0.51.0",
"0.52.0",
"0.52.1",
"0.6.0",
"0.6.1",
"0.6.2",
"0.6.3",
"0.7.0",
"0.7.1",
"0.7.2",
"0.7.3",
"0.7.4",
"0.8.0",
"0.8.1",
"0.8.2",
"0.8.3",
"0.8.4",
"0.8.5",
"0.8.6",
"0.8.7",
"0.8.8",
"0.9.0",
"0.9.1",
"0.9.10",
"0.9.11",
"0.9.2",
"0.9.3",
"0.9.4",
"0.9.5",
"0.9.6",
"0.9.7",
"0.9.8",
"0.9.9",
"1.0.0",
"1.0.0rc1",
"1.0.1",
"1.1.0",
"1.2.0",
"1.2.1"
]
}
],
"aliases": [
"CVE-2026-54282",
"GHSA-jp82-jpqv-5vv3"
],
"details": "Starlette is a lightweight ASGI framework/toolkit. Prior to 1.3.0, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host. This vulnerability is fixed in 1.3.0.",
"id": "PYSEC-2026-248",
"modified": "2026-06-27T10:29:54.933884Z",
"published": "2026-06-22T18:16:46.807Z",
"references": [
{
"type": "ADVISORY",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
BREW-AIDER-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:35 – Updated: 2026-09-09 23:40 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": null,
"range_state": "affected",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@0.52.1",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "aider",
"purl": "pkg:brew/aider"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@0.52.1",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "0.52.1"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-aider-CVE-2026-54282",
"modified": "2026-09-09T23:40:56Z",
"published": "2026-08-13T16:35:12Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-CYCODE-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:42 – Updated: 2026-09-28 17:12 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.7.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "cycode",
"purl": "pkg:brew/cycode"
},
"ranges": [
{
"events": [
{
"introduced": "3.2.0"
},
{
"fixed": "3.16.1_1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.7.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.7.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-cycode-CVE-2026-54282",
"modified": "2026-09-28T17:12:16Z",
"published": "2026-08-13T16:42:07Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-DSTACK-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:43 – Updated: 2026-09-30 19:10 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.7.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "dstack",
"purl": "pkg:brew/dstack"
},
"ranges": [
{
"events": [
{
"introduced": "0.0.14"
},
{
"fixed": "0.21.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.7.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.7.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-dstack-CVE-2026-54282",
"modified": "2026-09-30T19:10:43Z",
"published": "2026-08-13T16:43:57Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-ESPHOME-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:45 – Updated: 2026-09-09 23:53 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": null,
"range_state": "affected",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@0.52.1",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "esphome",
"purl": "pkg:brew/esphome"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@0.52.1",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "0.52.1"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-esphome-CVE-2026-54282",
"modified": "2026-09-09T23:53:49Z",
"published": "2026-08-13T16:45:08Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-FASTAPI-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:46 – Updated: 2026-10-01 10:23 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.7.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "fastapi",
"purl": "pkg:brew/fastapi"
},
"ranges": [
{
"events": [
{
"introduced": "0.111.0"
},
{
"fixed": "0.137.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.7.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.7.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-fastapi-CVE-2026-54282",
"modified": "2026-10-01T10:23:43Z",
"published": "2026-08-13T16:46:30Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-FASTMCP-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:46 – Updated: 2026-09-25 10:27 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.7.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "fastmcp",
"purl": "pkg:brew/fastmcp"
},
"ranges": [
{
"events": [
{
"introduced": "2.12.3"
},
{
"fixed": "3.4.2_1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.7.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.7.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-fastmcp-CVE-2026-54282",
"modified": "2026-09-25T10:27:39Z",
"published": "2026-08-13T16:46:31Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-GITINGEST-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:51 – Updated: 2026-09-20 10:49 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.6.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "gitingest",
"purl": "pkg:brew/gitingest"
},
"ranges": [
{
"events": [
{
"introduced": "0.3.1"
},
{
"fixed": "0.3.1_8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.6.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.6.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-gitingest-CVE-2026-54282",
"modified": "2026-09-20T10:49:33Z",
"published": "2026-08-13T16:51:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-GLANCES-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:51 – Updated: 2026-09-28 18:24 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.7.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "glances",
"purl": "pkg:brew/glances"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.5.6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.7.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.7.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-glances-CVE-2026-54282",
"modified": "2026-09-28T18:24:14Z",
"published": "2026-08-13T16:51:23Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-GPTME-CVE-2026-54282 (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:54 – Updated: 2026-09-17 18:12 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.6.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "gptme",
"purl": "pkg:brew/gptme"
},
"ranges": [
{
"events": [
{
"introduced": "0.28.0"
},
{
"fixed": "0.31.0_12"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.6.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.6.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-gptme-CVE-2026-54282",
"modified": "2026-09-17T18:12:06Z",
"published": "2026-08-13T16:54:46Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
BREW-HERMES-AGENT-CVE-20… (GHSA-JP82-JPQV-5VV3)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:56 – Updated: 2026-09-10 19:27 – Source websiteSummary
In affected versions, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled. Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host.
Details
When a client requests a path that does not start with /:
GET @google.com HTTP/1.1
Host: localhost
affected versions reconstruct the URL as http://localhost@google.com. Per RFC 3986 §3.2.1, the substring before @ in the authority is userinfo, so re-parsing yields username = "localhost" and hostname = "google.com", with an empty path:
request.url == "http://localhost@google.com"
request.url.hostname == "google.com"
request.url.path == ""
The root cause is that the path is concatenated directly after the host without a separating /, and without validating that it begins with one. Only the Host header was validated when constructing request.url; the path was not.
This requires an ASGI server that forwards a request-target lacking a leading / into scope["path"].
Impact
Any application running an affected version that uses request.url, request.url.netloc, or request.url.hostname for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.
Note that this is less exploitable than GHSA-86qp-5c8j-p5mr: there, the poison is carried in the Host header, so the real path still routes to a valid endpoint while request.url.path lies. Here, the poison must be carried in the path itself, and that path (@google.com) does not match any registered route, so routing returns 404 and no endpoint handler runs. The exposure is limited to code that reads request.url before routing - notably middleware - or in 404/exception handlers.
Mitigation
Upgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields http://localhost/@google.com with request.url.hostname == "localhost".
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "starlette",
"resource_purl": "pkg:pypi/starlette@1.6.0",
"upstream_fixed_in": "1.3.0"
},
"package": {
"ecosystem": "Homebrew",
"name": "hermes-agent",
"purl": "pkg:brew/hermes-agent"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2026.8.3_1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/starlette@1.6.0",
"name": "starlette",
"resource": "starlette",
"strategy": "registry",
"subject_version": "1.6.0"
}
]
},
"details": "### Summary\n\nIn affected versions, the HTTP request path is not validated before being used to reconstruct `request.url`. Because `request.url` is rebuilt by concatenating `{scheme}://{host}{path}` and re-parsing the result, a path that does not begin with `/` (for example `@google.com`) moves the authority boundary during re-parsing, so `request.url.hostname` and `request.url.netloc` become attacker-controlled. Code that reads `request.url.hostname` (rather than the `Host` header or `scope`) can therefore be misled into trusting an attacker-supplied host.\n\n### Details\n\nWhen a client requests a path that does not start with `/`:\n\n```http\nGET @google.com HTTP/1.1\nHost: localhost\n```\n\naffected versions reconstruct the URL as `http://localhost@google.com`. Per [RFC 3986 \u00a73.2.1](https://www.rfc-editor.org/rfc/rfc3986.html#section-3.2.1), the substring before `@` in the authority is `userinfo`, so re-parsing yields `username = \"localhost\"` and `hostname = \"google.com\"`, with an empty path:\n\n```text\nrequest.url == \"http://localhost@google.com\"\nrequest.url.hostname == \"google.com\"\nrequest.url.path == \"\"\n```\n\nThe root cause is that the path is concatenated directly after the host without a separating `/`, and without validating that it begins with one. Only the `Host` header was validated when constructing `request.url`; the path was not.\n\nThis requires an ASGI server that forwards a request-target lacking a leading `/` into `scope[\"path\"]`.\n\n### Impact\n\nAny application running an affected version that uses `request.url`, `request.url.netloc`, or `request.url.hostname` for a security-sensitive decision (host-based authorization, redirect/callback base, SSRF target, cache key, audit log) may be affected, when no fronting proxy or load balancer rejects the malformed request-target first.\n\nNote that this is less exploitable than [GHSA-86qp-5c8j-p5mr](https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr): there, the poison is carried in the `Host` header, so the real path still routes to a valid endpoint while `request.url.path` lies. Here, the poison must be carried in the path itself, and that path (`@google.com`) does not match any registered route, so routing returns `404` and no endpoint handler runs. The exposure is limited to code that reads `request.url` before routing - notably middleware - or in 404/exception handlers.\n\n### Mitigation\n\nUpgrade to a patched version, which prevents the request path from crossing into the URL authority. The request above instead yields `http://localhost/@google.com` with `request.url.hostname == \"localhost\"`.",
"id": "BREW-hermes-agent-CVE-2026-54282",
"modified": "2026-09-10T19:27:17Z",
"published": "2026-08-13T16:56:26Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Kludex/starlette/security/advisories/GHSA-jp82-jpqv-5vv3"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54282"
},
{
"type": "PACKAGE",
"url": "https://github.com/Kludex/starlette"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-248.yaml"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Starlette: Unvalidated request path concatenated into authority poisons request.url.hostname",
"upstream": [
"GHSA-jp82-jpqv-5vv3",
"CVE-2026-54282",
"PYSEC-2026-248"
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.