Vulnerability · Published Sep 7, 2026 · Assigned by EEF

CVE-2026-82754ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls

Medium 6.3

In plain English

A medium-severity security flaw in ash_authentication_oauth2_server from ash-project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities).

Severity (CVSS 4.0)6.3Medium

Exploit odds (30 days)0.7%top 47.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
ash-project	ash_authentication_oauth2_server	0.1.0 – before 0.3.1
ash-project	ash_authentication_oauth2_server	855b578037c5ded18e8a6e60f42e56bde4905fae – before a72972d7ed3eb74c05dfa0653a258ef14454459a

Weakness: CWE-424 · 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

In plain English

Official description

Affected products (as reported)

References