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.
How to fix
- ash-project ash_authentication_oauth2_server0.3.1, a72972d7ed3eb74c05dfa0653a258ef14454459a or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| ash-project ash_authentication_oauth2_server | 0.1.0 ≤ v < 0.3.1, 855b578037c5ded18e8a6e60f42e56bde4905fae ≤ v < a72972d7ed3eb74c05dfa0653a258ef14454459a | 0.3.1, a72972d7ed3eb74c05dfa0653a258ef14454459a |
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