Vulnerability in Red Hat Build Of Keycloak
CVE-2026-11800
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (20.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 20.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
Weakness classification (CWE)
References
- access.redhat.com/errata/RHSA-2026:30083 (vendor-advisory, Vendor Advisory)
- access.redhat.com/errata/RHSA-2026:30084 (vendor-advisory, Vendor Advisory)
- access.redhat.com/security/cve/CVE-2026-11800 (vdb-entry, Vendor Advisory)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Vendor Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-11800?
- CVE-2026-11800 is a high-severity vulnerability in Red Hat Build Of Keycloak, classified under Improper Verification of Cryptographic Signature. CVSS score: 8.1/10. Published 2026-06-25.
- How severe is CVE-2026-11800?
- High severity. CVSS v3 base score is 8.1 out of 10.