Vulnerability-Lookup

GHSA-WJR9-J795-JXCR

Vulnerability from github – Published: 2026-10-23 21:37 – Updated: 2026-10-23 21:37

Summary

fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization

Details

Impact

fast-uri versions >= 2.4.2, <= 2.4.7, >= 3.1.3, <= 3.1.8, and >= 4.0.1, <= 4.2.2 can silently rewrite the host of an HTTP-family URL (http, https, ws, wss, or any scheme with domainHost: true). For those schemes canonicalizeHost() passes the parsed host to the WHATWG URL parser and adopts its .hostname without checking that the parser read the whole input as a host. RFC 3986 permits @ inside the host group and the WHATWG parser strips TAB, LF, and CR, so the authority fast-uri reports is rewritten by that second parser with no error set: data before an @ is dropped and whitespace is removed.

For example, fast-uri parses http://a@b@evil.example/ to host evil.example (dropping the b segment), and a host containing a raw TAB, CR, or LF has those characters stripped. equal() then treats a whitespace-smuggled host as the same as the clean one, and resolve() rewrites the authority the same way.

Applications that use fast-uri to enforce host-based policy (denylists, loopback filtering, redirect validation, outbound proxy routing) on one representation, such as the raw input, see a policy/use desync: the canonical host fast-uri returns differs from what was checked, and traffic can be steered to an unintended destination.

Patches

Upgrade to fast-uri 2.4.8, 3.1.9, or 4.2.3.

Workarounds

Reject URIs whose authority contains more than one @, or contains TAB, CR, or LF, before calling fast-uri. Alternatively, treat any non-empty parse(x).error as fatal, and compare hosts only from the same parse() result.

Severity

4.8 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "fast-uri"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.4.2"
            },
            {
              "fixed": "2.4.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "fast-uri"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.1.3"
            },
            {
              "fixed": "3.1.9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "fast-uri"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.1"
            },
            {
              "fixed": "4.2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-110180"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20",
      "CWE-436"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-23T21:37:59Z",
    "nvd_published_at": "2026-10-20T07:17:08Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\n`fast-uri` versions `\u003e= 2.4.2, \u003c= 2.4.7`, `\u003e= 3.1.3, \u003c= 3.1.8`, and `\u003e= 4.0.1, \u003c= 4.2.2` can silently rewrite the host of an HTTP-family URL (`http`, `https`, `ws`, `wss`, or any scheme with `domainHost: true`). For those schemes `canonicalizeHost()` passes the parsed host to the WHATWG `URL` parser and adopts its `.hostname` without checking that the parser read the whole input as a host. RFC 3986 permits `@` inside the host group and the WHATWG parser strips TAB, LF, and CR, so the authority `fast-uri` reports is rewritten by that second parser with no `error` set: data before an `@` is dropped and whitespace is removed.\n\nFor example, `fast-uri` parses `http://a@b@evil.example/` to host `evil.example` (dropping the `b` segment), and a host containing a raw TAB, CR, or LF has those characters stripped. `equal()` then treats a whitespace-smuggled host as the same as the clean one, and `resolve()` rewrites the authority the same way.\n\nApplications that use `fast-uri` to enforce host-based policy (denylists, loopback filtering, redirect validation, outbound proxy routing) on one representation, such as the raw input, see a policy/use desync: the canonical host `fast-uri` returns differs from what was checked, and traffic can be steered to an unintended destination.\n\n### Patches\n\nUpgrade to `fast-uri` `2.4.8`, `3.1.9`, or `4.2.3`.\n\n### Workarounds\n\nReject URIs whose authority contains more than one `@`, or contains TAB, CR, or LF, before calling `fast-uri`. Alternatively, treat any non-empty `parse(x).error` as fatal, and compare hosts only from the same `parse()` result.",
  "id": "GHSA-wjr9-j795-jxcr",
  "modified": "2026-10-23T21:37:59Z",
  "published": "2026-10-23T21:37:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/security/advisories/GHSA-wjr9-j795-jxcr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-110180"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/commit/58c183d0b168ad87f98773266444ce1f6375803a"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/commit/ddfc6a51122dfce0365655f04479fc3adb7f6b3c"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/commit/f6d46dfeab025d0c440485f4ae29fa4f14707646"
    },
    {
      "type": "WEB",
      "url": "https://cna.openjsf.org/security-advisories.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fastify/fast-uri"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/releases/tag/v2.4.8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/releases/tag/v3.1.9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fastify/fast-uri/releases/tag/v4.2.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization"
}

CVE-2026-110180 (GCVE-0-2026-110180)

Vulnerability from cvelistv5 – Published: 2026-10-20 07:00 – Updated: 2026-10-20 16:06

Title

fast-uri vulnerable to host confusion via unchecked WHATWG host canonicalization

Summary

fast-uri is a dependency-free RFC 3986 URI parser and serializer for Node.js. In versions from 2.4.2 through 2.4.7, from 3.1.3 through 3.1.8, and from 4.0.1 through 4.2.2, for HTTP-family schemes the canonicalizeHost() function passes the parsed host to the WHATWG URL parser and adopts its hostname without checking that the parser consumed the entire input as a host, so the authority can be silently rewritten: data before an at-sign is dropped and tab, carriage-return, and line-feed characters are stripped, with no error reported. An application that enforces host-based policy such as denylists, loopback filtering, redirect validation, or outbound proxy routing on one representation can then see the canonical host diverge from what it checked, allowing traffic to be steered to an unintended destination. The issue is fixed in fast-uri 2.4.8, 3.1.9, and 4.2.3, and users should upgrade to one of these versions or later. As a workaround, reject an authority that contains more than one at-sign or any tab, carriage-return, or line-feed before calling fast-uri, or treat any non-empty parse error as fatal and compare hosts only from the same parse result.

Severity

4.8 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-20 16:06 UTC

CWE

CWE-20 - Improper Input Validation
CWE-436 - Interpretation Conflict

Assigner

openjs CNA under the redhat root

CNA scorecard C 65/100 over 121 records in the last 180 days details

References

2 references

URL	Tags
https://github.com/fastify/fast-uri/security/advi…
https://cna.openjsf.org/security-advisories.html

Impacted products

1 product

Vendor	Product	Version
fast-uri	fast-uri	Affected: 2.4.2 , < 2.4.8 (semver) Unaffected: 2.4.8 (semver) Affected: 3.1.3 , < 3.1.9 (semver) Unaffected: 3.1.9 (semver) Affected: 4.0.1 , < 4.2.3 (semver) Unaffected: 4.2.3 (semver)

Credits

UlisesGascon mcollina zekth

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JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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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.

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