{"id":"CVE-2026-82754","title":"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_ser…","summary":"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_ser…","severity":"medium","cvss":6.3,"cvssVector":"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","cwe":["CWE-424"],"vendor":"ash-project","product":"ash_authentication_oauth2_server","affected":["ash_authentication_oauth2_server >= 0.1.0 < 0.3.1","ash-project/ash_authentication_oauth2_server >= 855b578037c5ded18e8a6e60f42e56bde4905fae < a72972d7ed3eb74c05dfa0653a258ef14454459a"],"published":"2026-09-07","updated":"2026-09-08","sourceUpdated":"2026-09-08T15:18:50.320","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-82754","references":[{"url":"https://cna.erlef.org/cves/CVE-2026-82754.html","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wwxg-h779-3wf4","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-82754","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-08T14:41:33.862078Z"},"cvssSource":"cna","epss":0.00691,"epssPercentile":0.50718,"ingestedAt":"2026-09-08T15:33:26.980Z","slug":"CVE-2026-82754","body":"## Overview\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## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":35,"depthScoreParts":{"impact":34.7,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}