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.
Weakness
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Build_of_keycloak | Redhat | 26.6 (including) | 26.6.4 (excluding) |
| Red Hat build of Keycloak 26.6 | RedHat | rhbk/keycloak-operator-bundle:26.6.4-2 | * |
| Red Hat build of Keycloak 26.6 | RedHat | rhbk/keycloak-rhel9:26.6-8 | * |
| Red Hat build of Keycloak 26.6 | RedHat | rhbk/keycloak-rhel9-operator:26.6-8 | * |
| Red Hat build of Keycloak 26.6.4 | RedHat | * |
Related Attack Patterns
References
- https://access.redhat.com/errata/RHSA-2026:30083
- https://access.redhat.com/errata/RHSA-2026:30084
- https://access.redhat.com/security/cve/CVE-2026-11800
- https://bugzilla.redhat.com/show_bug.cgi?id=2487006
- https://access.redhat.com/errata/RHSA-2026:30083
- https://access.redhat.com/errata/RHSA-2026:30084
- https://access.redhat.com/security/cve/CVE-2026-11800
- https://bugzilla.redhat.com/show_bug.cgi?id=2487006
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.json