A flaw was found in Keycloak. When the JSON Web Token (JWT) authorization grant preview feature is enabled and a user account is disabled, Keycloak fails to validate the user’s disabled status during JWT authorization grant processing. A remote attacker with low privileges can exploit this improper access control vulnerability by presenting a valid assertion token from an external identity provider to obtain a JWT for a disabled user. This allows unauthorized access to sensitive resources.
Weakness
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
Extended Description
Access control involves the use of several protection mechanisms such as:
When any mechanism is not applied or otherwise fails, attackers can compromise the security of the product by gaining privileges, reading sensitive information, executing commands, evading detection, etc. There are two distinct behaviors that can introduce access control weaknesses:
Potential Mitigations
- Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
- Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/19.html
- https://cwe.mitre.org/data/definitions/441.html
- https://cwe.mitre.org/data/definitions/478.html
- https://cwe.mitre.org/data/definitions/479.html
- https://cwe.mitre.org/data/definitions/502.html
- https://cwe.mitre.org/data/definitions/503.html
- https://cwe.mitre.org/data/definitions/536.html
- https://cwe.mitre.org/data/definitions/546.html
- https://cwe.mitre.org/data/definitions/550.html
- https://cwe.mitre.org/data/definitions/551.html
- https://cwe.mitre.org/data/definitions/552.html
- https://cwe.mitre.org/data/definitions/556.html
- https://cwe.mitre.org/data/definitions/558.html
- https://cwe.mitre.org/data/definitions/562.html
- https://cwe.mitre.org/data/definitions/563.html
- https://cwe.mitre.org/data/definitions/564.html
- https://cwe.mitre.org/data/definitions/578.html
References
- https://access.redhat.com/security/cve/CVE-2026-1609
- https://bugzilla.redhat.com/show_bug.cgi?id=2435257
- https://github.com/keycloak/keycloak/issues/46144
- https://github.com/keycloak/keycloak/releases/tag/26.5.3
- https://access.redhat.com/security/cve/CVE-2026-1609
- https://bugzilla.redhat.com/show_bug.cgi?id=2435257
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-1609.json