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.

CVSS 3.1

8.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 22% of CVEs (scores of 2026-10-25)

CWE

CWE-347

Published

2026-06-25

Modified

2026-10-25

Record from

the NVD, synced 2026-10-25

Affected

• redhat:build_of_keycloak

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

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