Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-02-16T08:08:00 keycloak: Keycloak: Denial of Service due to excessive SAMLRequest decompression 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L CWE-409

A flaw was found in Keycloak. An unauthenticated remote attacker can trigger an application level Denial of Service (DoS) by sending a highly compressed SAMLRequest through the SAML Redirect Binding. The server fails to enforce size limits during DEFLATE decompression, leading to an OutOfMemoryError (OOM) and subsequent process termination. This vulnerability allows an attacker to disrupt the availability of the service.

This MODERATE impact denial of service flaw affects Red Hat Build of Keycloak (RHBK). An unauthenticated remote attacker can exploit this by sending a highly compressed SAMLRequest through the SAML Redirect Binding. The server's inability to enforce size limits during DEFLATE decompression leads to an OutOfMemoryError, causing process termination and disrupting service availability. This vulnerability is applicable when Keycloak is configured to use SAML Redirect Binding. Red Hat would like to thank Sho Odagiri (GMO Cybersecurity by Ierae, Inc.) for reporting this issue. Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Red Hat build of Keycloak 26.4 2026-03-05T00:00:00Z RHSA-2026:3948 rhbk/keycloak-operator-bundle:26.4.10-1 Red Hat build of Keycloak 26.4 2026-03-05T00:00:00Z RHSA-2026:3948 rhbk/keycloak-rhel9:26.4-12 Red Hat build of Keycloak 26.4 2026-03-05T00:00:00Z RHSA-2026:3948 rhbk/keycloak-rhel9-operator:26.4-12 Red Hat build of Keycloak 26.4.10 2026-03-05T00:00:00Z RHSA-2026:3947 rhbk/keycloak-rhel9 https://www.cve.org/CVERecord?id=CVE-2026-2575 https://nvd.nist.gov/vuln/detail/CVE-2026-2575