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. 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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| Hex | ash_authentication_oauth2_server | >=0.1.0,<0.3.1 | 0.3.1 |
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
- https://osv.dev/vulnerability/EEF-CVE-2026-82754
CWEs
CWE-424
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.