Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Redhat | Build Of Keycloak | >= 26.6, < 26.6.4 |
Related Weaknesses (CWE)
References
- https://access.redhat.com/errata/RHSA-2026:30083Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:30084Vendor Advisory
- https://access.redhat.com/security/cve/CVE-2026-11800Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2487006Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:30083Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:30084Vendor Advisory
- https://access.redhat.com/security/cve/CVE-2026-11800Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2487006Vendor Advisory
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.jsonVendor Advisory
FAQ
What is CVE-2026-11800?
CVE-2026-11800 is a vulnerability with a CVSS score of 8.1 (HIGH). 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 forgi...
How severe is CVE-2026-11800?
CVE-2026-11800 has been rated HIGH with a CVSS base score of 8.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-11800?
Check the references section above for vendor advisories and patch information. Affected products include: Redhat Build Of Keycloak.