EEF-CVE-2026-82754

Dashboard / Vulnerabilities / EEF-CVE-2026-82754

EEF-CVE-2026-82754

Summary: ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls

Details: ## 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. 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. This issue affects ash\_authentication\_oauth2\_server: from 0.1.0 before 0.3.1. ## Configuration 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.

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://github.com/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a, https://hex.pm/packages/ash_authentication_oauth2_server