CVE-2026-9801 MEDIUM

CVE-2026-9801: Keycloak: keycloak: denial of service via malformed ldap password policy response

Vendor Red Hat
Product Red Hat build of Keycloak 26.6.3
Weakness CWE-1284
Published May 28, 2026
Last update June 10, 2026

CVSS base score

4.9/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction None
Confidentiality None
Integrity None

CVSS vector

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

What the vulnerability does

01Description

A flaw was found in Keycloak. A remote attacker with high privileges, such as a realm administrator configuring a malicious Lightweight Directory Access Protocol (LDAP) server or an attacker compromising an upstream LDAP server, could exploit this vulnerability. By sending a malformed LDAP password policy response during a password authentication request, the attacker can trigger an OutOfMemoryError. This causes the Keycloak Java Virtual Machine (JVM) to terminate, leading to a denial of service (DoS) for all realms on the affected node.

Key dates

02Disclosure timeline

May 28, 2026 CVE published
June 10, 2026 Record updated