CVE-2026-82754 (GCVE-0-2026-82754)
Vulnerability from cvelistv5 – Published: 2026-09-07 22:23 – Updated: 2026-09-08 14:41
VLAI
EPSS
VEX
Title
ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls
Summary
Improper Protection of Alternate Path vulnerability in ash-project ash_authentication_oauth2_server exposes the state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix.
oauth2_server_protocol_routes/1 in AshAuthentication.Phoenix.Oauth2Server.Router forwards the same ProtocolRouter at both the /oauth prefix and the /.well-known prefix. Phoenix forward strips the matched prefix before dispatch, so the full route table answers under both mounts, and POST /register, POST /token, and POST /revoke are reachable as /.well-known/register, /.well-known/token, and /.well-known/revoke. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the /oauth paths, or that allow-list /.well-known as unauthenticated, do not apply to the alias.
This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-08 14:41 UTC
CWE
- CWE-424 - Improper Protection of Alternate Path
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/ash-project/ash_authentication… | vendor-advisoryrelated |
| https://cna.erlef.org/cves/CVE-2026-82754.html | related |
| https://osv.dev/vulnerability/EEF-CVE-2026-82754 | related |
| https://github.com/ash-project/ash_authentication… | patch |
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| ash-project | ash_authentication_oauth2_server |
Affected:
0.1.0 , < 0.3.1
(semver)
cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:* |
||
| ash-project | ash_authentication_oauth2_server |
Affected:
855b578037c5ded18e8a6e60f42e56bde4905fae , < a72972d7ed3eb74c05dfa0653a258ef14454459a
(git)
cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:* |
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"lib/ash_authentication_phoenix/oauth2_server/router.ex",
"lib/ash_authentication_phoenix/oauth2_server/protocol_router.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.AshAuthentication.Phoenix.Oauth2Server.Router\u0027:oauth2_server_protocol_routes/1"
},
{
"name": "\u0027Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter\u0027:call/2"
}
],
"repo": "https://github.com/ash-project/ash_authentication_oauth2_server",
"vendor": "ash-project",
"versions": [
{
"lessThan": "0.3.1",
"status": "affected",
"version": "0.1.0",
"versionType": "semver"
}
]
},
{
"collectionURL": "https://github.com",
"cpes": [
"cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"
],
"defaultStatus": "unaffected",
"modules": [
"\u0027Elixir.AshAuthentication.Phoenix.Oauth2Server.Router\u0027",
"\u0027Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter\u0027"
],
"packageName": "ash-project/ash_authentication_oauth2_server",
"packageURL": "pkg:github/ash-project/ash_authentication_oauth2_server",
"product": "ash_authentication_oauth2_server",
"programFiles": [
"lib/ash_authentication_phoenix/oauth2_server/router.ex",
"lib/ash_authentication_phoenix/oauth2_server/protocol_router.ex"
],
"programRoutines": [
{
"name": "\u0027Elixir.AshAuthentication.Phoenix.Oauth2Server.Router\u0027:oauth2_server_protocol_routes/1"
},
{
"name": "\u0027Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter\u0027:call/2"
}
],
"repo": "https://github.com/ash-project/ash_authentication_oauth2_server",
"vendor": "ash-project",
"versions": [
{
"lessThan": "a72972d7ed3eb74c05dfa0653a258ef14454459a",
"status": "affected",
"version": "855b578037c5ded18e8a6e60f42e56bde4905fae",
"versionType": "git"
}
]
}
],
"configurations": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eThe routing alias is unconditional. Exploitable impact depends on the deployment applying path-scoped edge controls (WAF, rate limiting, auth-redirect exemptions) to the \u003ccode\u003e/oauth\u003c/code\u003e prefix, or allow-listing \u003ccode\u003e/.well-known\u003c/code\u003e as unauthenticated, that the alias then bypasses.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"value": "The routing alias is unconditional. Exploitable impact depends on the deployment applying path-scoped edge controls (WAF, rate limiting, auth-redirect exemptions) to the `/oauth` prefix, or allow-listing `/.well-known` as unauthenticated, that the alias then bypasses."
}
],
"value": "The routing alias is unconditional. Exploitable impact depends on the deployment applying path-scoped edge controls (WAF, rate limiting, auth-redirect exemptions) to the /oauth prefix, or allow-listing /.well-known as unauthenticated, that the alias then bypasses."
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*",
"versionEndExcluding": "0.3.1",
"versionStartIncluding": "0.1.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
],
"operator": "AND"
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "reporter",
"value": "Peter Ullrich"
},
{
"lang": "en",
"type": "remediation developer",
"value": "Zach Daniel / Ash Project"
},
{
"lang": "en",
"type": "coordinator",
"value": "Jonatan M\u00e4nnchen / EEF"
}
],
"descriptions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eImproper Protection of Alternate Path vulnerability in ash-project ash_authentication_oauth2_server exposes the state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix.\u003c/p\u003e\n\u003cp\u003e\u003ccode\u003eoauth2_server_protocol_routes/1\u003c/code\u003e in \u003ccode\u003eAshAuthentication.Phoenix.Oauth2Server.Router\u003c/code\u003e forwards the same \u003ccode\u003eProtocolRouter\u003c/code\u003e at both the \u003ccode\u003e/oauth\u003c/code\u003e prefix and the \u003ccode\u003e/.well-known\u003c/code\u003e prefix. Phoenix \u003ccode\u003eforward\u003c/code\u003e strips the matched prefix before dispatch, so the full route table answers under both mounts, and \u003ccode\u003ePOST /register\u003c/code\u003e, \u003ccode\u003ePOST /token\u003c/code\u003e, and \u003ccode\u003ePOST /revoke\u003c/code\u003e are reachable as \u003ccode\u003e/.well-known/register\u003c/code\u003e, \u003ccode\u003e/.well-known/token\u003c/code\u003e, and \u003ccode\u003e/.well-known/revoke\u003c/code\u003e. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the \u003ccode\u003e/oauth\u003c/code\u003e paths, or that allow-list \u003ccode\u003e/.well-known\u003c/code\u003e as unauthenticated, do not apply to the alias.\u003c/p\u003e\n\u003cp\u003eThis issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.\u003c/p\u003e"
},
{
"base64": false,
"type": "text/markdown",
"value": "Improper Protection of Alternate Path vulnerability in ash-project ash_authentication_oauth2_server exposes the state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix.\n\n`oauth2_server_protocol_routes/1` in `AshAuthentication.Phoenix.Oauth2Server.Router` forwards the same `ProtocolRouter` at both the `/oauth` prefix and the `/.well-known` prefix. Phoenix `forward` strips the matched prefix before dispatch, so the full route table answers under both mounts, and `POST /register`, `POST /token`, and `POST /revoke` are reachable as `/.well-known/register`, `/.well-known/token`, and `/.well-known/revoke`. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the `/oauth` paths, or that allow-list `/.well-known` as unauthenticated, do not apply to the alias.\n\nThis issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1."
}
],
"value": "Improper Protection of Alternate Path vulnerability in ash-project ash_authentication_oauth2_server exposes the state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix.\n\noauth2_server_protocol_routes/1 in AshAuthentication.Phoenix.Oauth2Server.Router forwards the same ProtocolRouter at both the /oauth prefix and the /.well-known prefix. Phoenix forward strips the matched prefix before dispatch, so the full route table answers under both mounts, and POST /register, POST /token, and POST /revoke are reachable as /.well-known/register, /.well-known/token, and /.well-known/revoke. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the /oauth paths, or that allow-list /.well-known as unauthenticated, do not apply to the alias.\n\nThis issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1."
}
],
"impacts": [
{
"capecId": "CAPEC-554",
"descriptions": [
{
"lang": "en",
"value": "CAPEC-554 Functionality Bypass"
}
]
}
],
"metrics": [
{
"cvssV4_0": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"baseScore": 6.3,
"baseSeverity": "MEDIUM",
"privilegesRequired": "NONE",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "LOW",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-424",
"description": "CWE-424 Improper Protection of Alternate Path",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-07T22:23:56.762Z",
"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"shortName": "EEF"
},
"references": [
{
"tags": [
"vendor-advisory",
"related"
],
"url": "https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wwxg-h779-3wf4"
},
{
"tags": [
"related"
],
"url": "https://cna.erlef.org/cves/CVE-2026-82754.html"
},
{
"tags": [
"related"
],
"url": "https://osv.dev/vulnerability/EEF-CVE-2026-82754"
},
{
"tags": [
"patch"
],
"url": "https://github.com/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a"
}
],
"source": {
"discovery": "EXTERNAL"
},
"title": "ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls"
}
},
"cveMetadata": {
"assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
"assignerShortName": "EEF",
"cveId": "CVE-2026-82754",
"datePublished": "2026-09-07T22:23:56.762Z",
"dateReserved": "2026-08-31T01:00:10.817Z",
"dateUpdated": "2026-09-07T22:23:56.762Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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.
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.
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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.
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