CVE-2026-11800 HIGH

CVE-2026-11800: Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion

Vendor Red Hat
Product Red Hat build of Keycloak 26.6.4
Weakness CWE-347
Published June 25, 2026
Last update June 30, 2026

CVSS base score

8.1/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

June 25, 2026 CVE published
June 30, 2026 Record updated