CVE-2026-82758: Ash-Project Ash Authentication OAUTH2 Server

Medium severity, CVSS 6.3. EPSS: 0.7% chance of exploitation in the next 30 days.

Improper Authentication vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to register OAuth clients even when Dynamic Client Registration is gated by an initial access token. resolve_secret/3 in AshAuthentication.Oauth2Server (reached through __resolve_secret__!) treated any return other than {:ok, _} or :error from a configured {module, function, args} or 2-arity-function secret provider as a valid secret, wrapping nil, false, or "" as {:ok, value}. When the initial_access_token resolves to such an empty value, POST /oauth/register compares the presented bearer token against it and the comparison passes with no token supplied, so registration is open although it was configured closed. The same fail-open affected other resolved secrets such as signing_secret. This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.

Affected products

• Ash-Project Ash Authentication OAUTH2 Server: from 0.1.0, before 0.3.1 (fixed in 0.3.1)

Published 2026-09-07. Last modified 2026-09-08.