CVE-2026-11800

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.

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Produits concernés

• Red Hat build of Keycloak 26.6
• Red Hat build of Keycloak 26.6.4
• Red Hat Build of Keycloak
• Red Hat Data Grid 8
• Red Hat JBoss Enterprise Application Platform Expansion Pack
• Red Hat Single Sign-On 7
• Redhat build of keycloak

Scores CVSS

Faiblesses (CWE)

• CWE-347

Références

• https://access.redhat.com/errata/RHSA-2026:30083 Vendor Advisory
• https://access.redhat.com/errata/RHSA-2026:30084 Vendor Advisory
• https://access.redhat.com/security/cve/CVE-2026-11800 Vendor Advisory
• https://bugzilla.redhat.com/show_bug.cgi?id=2487006 Vendor Advisory
• https://access.redhat.com/errata/RHSA-2026:30083 Vendor Advisory
• https://access.redhat.com/errata/RHSA-2026:30084 Vendor Advisory
• https://access.redhat.com/security/cve/CVE-2026-11800 Vendor Advisory
• https://bugzilla.redhat.com/show_bug.cgi?id=2487006 Vendor Advisory
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-11800.json Vendor Advisory

Ailleurs

• NVD
• CVE.org
• CIRCL Vulnerability-Lookup
• CERT-FR
• GitHub Advisories