GHSA-gqj5-2xp5-3qmp

Duplicate Advisory: Authentication bypass via jwt algorithm confusion

Published

2026-06-26

Modified

2026-11-03

Sources

github-advisory

Summary

### Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-j97h-3f8r-mrjr. This link is maintained to preserve external references. ### Original Description A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.

Affected packages

Remediation: Upgrade to 26.6.4 or later.

References

• https://github.com/advisories/GHSA-gqj5-2xp5-3qmp