{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-82754", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-08-31T01:00:10.817Z", "datePublished": "2026-09-07T22:23:56.762Z", "dateUpdated": "2026-09-07T22:23:56.762Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router'", "'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter'"], "packageName": "ash_authentication_oauth2_server", "packageURL": "pkg:hex/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": "'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router':oauth2_server_protocol_routes/1"}, {"name": "'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter':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": ["'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router'", "'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter'"], "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": "'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router':oauth2_server_protocol_routes/1"}, {"name": "'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter':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": "<p>The routing alias is unconditional. Exploitable impact depends on the deployment applying path-scoped edge controls (WAF, rate limiting, auth-redirect exemptions) to the <code>/oauth</code> prefix, or allow-listing <code>/.well-known</code> as unauthenticated, that the alias then bypasses.</p>"}, {"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": "<p>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.</p>\n<p><code>oauth2_server_protocol_routes/1</code> in <code>AshAuthentication.Phoenix.Oauth2Server.Router</code> forwards the same <code>ProtocolRouter</code> at both the <code>/oauth</code> prefix and the <code>/.well-known</code> prefix. Phoenix <code>forward</code> strips the matched prefix before dispatch, so the full route table answers under both mounts, and <code>POST /register</code>, <code>POST /token</code>, and <code>POST /revoke</code> are reachable as <code>/.well-known/register</code>, <code>/.well-known/token</code>, and <code>/.well-known/revoke</code>. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the <code>/oauth</code> paths, or that allow-list <code>/.well-known</code> as unauthenticated, do not apply to the alias.</p>\n<p>This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.</p>"}, {"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": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-09-07T22:23:56.762Z"}, "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"}}}

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