{"id":"CVE-2026-82754","aliases":["EEF-CVE-2026-82754","EUVD-2026-72536","GHSA-wwxg-h779-3wf4"],"status":"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.","severity":{"version":"4.0","score":6.3,"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00691,"percentile":0.53326,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-424"],"published":"2026-09-07T22:23:56Z","modified":"2026-10-28T02:30:59Z","fixes":[{"ecosystem":"Hex","package":"ash_authentication_oauth2_server","fixed_in":["0.3.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Hex","package":"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"]}],"products":[{"vendor":"ash-project","product":"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","advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-82754.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82754","tags":["related","web"]},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a","tags":["patch","fix"]},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82754.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-82754","tags":["advisory"]},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server","tags":["package"]},{"url":"https://hex.pm/packages/ash_authentication_oauth2_server","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-82754","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.","status":"published","published":"2026-09-07T22:23:56.762Z","modified":"2026-09-08T14:41:45.077Z","cvss":[{"version":"4.0","score":6.3,"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","level":"medium","assessor":"cna"}],"cwes":["CWE-424"],"updated_at":"2026-11-02T13:40:35.004553Z"}],"euvd":[{"id":"EUVD-2026-72536","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.","status":"published","published":"2026-09-07T22:23:56Z","modified":"2026-09-08T14:41:45Z","cvss":[{"version":"4.0","score":6.3,"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","level":"medium"}],"updated_at":"2026-11-02T17:28:29.426Z"}],"nvd":[{"id":"CVE-2026-82754","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.","status":"published","published":"2026-09-07T23:16:52.403Z","modified":"2026-09-08T15:18:50.32Z","cvss":[{"version":"4.0","score":6.3,"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"}],"cwes":["CWE-424"],"updated_at":"2026-11-02T14:12:44.436435Z"}],"osv":[{"id":"CVE-2026-82754","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.","status":"published","published":"2026-09-07T22:23:56.762Z","modified":"2026-10-28T02:30:59.535980193Z","cvss":[{"version":"4.0","score":6.3,"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","level":"medium"}],"cwes":["CWE-424"],"updated_at":"2026-11-02T15:45:18.482949Z"},{"id":"EEF-CVE-2026-82754","title":"ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls","description":"## 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.","status":"published","published":"2026-09-07T22:23:56.762Z","modified":"2026-09-08T22:30:03.599782796Z","cvss":[{"version":"4.0","score":6.3,"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","level":"medium"}],"cwes":["CWE-424"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}