{"affected":[{"package":{"ecosystem":"Hex","name":"ash_authentication_oauth2_server","purl":"pkg:hex/ash_authentication_oauth2_server"},"ranges":[{"events":[{"introduced":"0.1.0"},{"fixed":"0.3.1"}],"type":"SEMVER"}],"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"]},{"ranges":[{"events":[{"introduced":"855b578037c5ded18e8a6e60f42e56bde4905fae"},{"fixed":"a72972d7ed3eb74c05dfa0653a258ef14454459a"}],"repo":"https://github.com/ash-project/ash_authentication_oauth2_server","type":"GIT"}]}],"aliases":["GHSA-wwxg-h779-3wf4","CVE-2026-82754"],"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"}],"database_specific":{"capec_ids":["CAPEC-554"],"cpe_ids":["cpe:2.3:a:ash-project:ash_authentication_oauth2_server:*:*:*:*:*:*:*:*"],"cwe_ids":["CWE-424"]},"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\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.\n\n## Configuration\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.","id":"EEF-CVE-2026-82754","modified":"2026-09-07T22:23:57.267771Z","published":"2026-09-07T22:23:56.762Z","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"}],"related":[],"schema_version":"1.7.3","severity":[{"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","type":"CVSS_V4"}],"summary":"ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls","upstream":[]}