{"id":"EEF-CVE-2026-82754","summary":"ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls","details":"## Summary\n\nImproper 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.\n\n## Configurations\n\nThe 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.","aliases":["CVE-2026-82754","GHSA-wwxg-h779-3wf4"],"modified":"2026-09-08T22:30:03.599782796Z","published":"2026-09-07T22:23:56.762Z","database_specific":{"cwe_ids":["CWE-424"],"capec_ids":["CAPEC-554"],"cpe_ids":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"]},"references":[{"type":"ADVISORY","url":"https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wwxg-h779-3wf4"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-82754.html"},{"type":"FIX","url":"https://github.com/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a"},{"type":"PACKAGE","url":"https://hex.pm/packages/ash_authentication_oauth2_server"}],"affected":[{"package":{"name":"ash_authentication_oauth2_server","ecosystem":"Hex","purl":"pkg:hex/ash_authentication_oauth2_server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"0.3.1"}]}],"versions":["0.1.0","0.1.1","0.1.2","0.1.3","0.2.0","0.2.1","0.2.2","0.3.0"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-82754.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/ash-project/ash_authentication_oauth2_server","events":[{"introduced":"855b578037c5ded18e8a6e60f42e56bde4905fae"},{"fixed":"a72972d7ed3eb74c05dfa0653a258ef14454459a"}]}],"versions":["v0.3.0","v0.2.2","v0.2.1","v0.2.0","v0.1.3","v0.1.2","v0.1.1","v0.1.0"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-82754.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}],"credits":[{"name":"Peter Ullrich","type":"FINDER"},{"name":"Peter Ullrich","type":"REPORTER"},{"name":"Zach Daniel / Ash Project","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen / EEF","type":"COORDINATOR"}]}