CVE-2026-82758
Severity CVSS v4.0:
MEDIUM
Type:
CWE-287
Authentication Issues
Publication date:
07/09/2026
Last modified:
07/09/2026
Description
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.<br />
<br />
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.<br />
<br />
This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.
Impact
Base Score 4.0
6.30
Severity 4.0
MEDIUM
References to Advisories, Solutions, and Tools
- https://cna.erlef.org/cves/CVE-2026-82758.html
- https://github.com/ash-project/ash_authentication_oauth2_server/commit/30a87101871775d27d79f9ad6f29eafa4779e118
- https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-fxc6-vp68-87pw
- https://osv.dev/vulnerability/EEF-CVE-2026-82758