{"id":"CVE-2026-82754","state":"PUBLISHED","title":"ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls","description":"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.","publishedAt":"2026-09-07T22:23:56.762Z","updatedAt":"2026-09-08T14:41:45.077Z","severity":{"score":6.3,"label":"Medium","version":"4.0","vector":"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","source":"EEF"},"assigner":"EEF","products":["ash-project ash_authentication_oauth2_server"],"affected":[{"vendor":"ash-project","product":"ash_authentication_oauth2_server","packageName":"ash_authentication_oauth2_server","packageURL":"pkg:hex/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"0.3.1","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router'","'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter'"],"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","product":"ash_authentication_oauth2_server","packageName":"ash-project/ash_authentication_oauth2_server","packageURL":"pkg:github/ash-project/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"855b578037c5ded18e8a6e60f42e56bde4905fae","status":"affected","lessThan":"a72972d7ed3eb74c05dfa0653a258ef14454459a","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router'","'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter'"],"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"}],"references":["https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wwxg-h779-3wf4","https://cna.erlef.org/cves/CVE-2026-82754.html","https://osv.dev/vulnerability/EEF-CVE-2026-82754","https://github.com/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a"],"weaknesses":["CWE-424"],"ingestedAt":"2026-10-29T20:13:15.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/82xxx/CVE-2026-82754.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-82754","state":"PUBLISHED","datePublished":"2026-09-07T22:23:56.762Z","dateUpdated":"2026-09-08T14:41:45.077Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-08-31T01:00:10.817Z"},"containers":{"cna":{"title":"ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls","descriptions":[{"lang":"en","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."}],"affected":[{"vendor":"ash-project","product":"ash_authentication_oauth2_server","packageName":"ash_authentication_oauth2_server","packageURL":"pkg:hex/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"0.3.1","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router'","'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter'"],"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","product":"ash_authentication_oauth2_server","packageName":"ash-project/ash_authentication_oauth2_server","packageURL":"pkg:github/ash-project/ash_authentication_oauth2_server","defaultStatus":"unaffected","versions":[{"version":"855b578037c5ded18e8a6e60f42e56bde4905fae","status":"affected","lessThan":"a72972d7ed3eb74c05dfa0653a258ef14454459a","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshAuthentication.Phoenix.Oauth2Server.Router'","'Elixir.AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter'"],"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"}],"references":[{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wwxg-h779-3wf4","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-82754.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82754","tags":["related"]},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a","tags":["patch"]}],"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":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-09-07T22:23:56.762Z"},"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 Männchen / EEF"}],"impacts":[{"capecId":"CAPEC-554","descriptions":[{"lang":"en","value":"CAPEC-554 Functionality Bypass"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-08T14:41:33.862078Z","id":"CVE-2026-82754","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-08T14:41:45.077Z"}}]}}}