CVE-2026-9801

Medium

Description

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.

SeverityMedium

CVSS4.9

Exploit probability—

Product

Redhat Build Of Keycloak

PublishedMay 28, 2026

First seenMay 28, 2026

Weakness typeCWE-1284CWE-1284

How to fix

Update

org.keycloak:keycloak-ldap-federation26.6.3 or later

Vendor advisories

Affected products

Product	Affected versions	Fixed in
redhat build_of_keycloak	No range specified	—
org.keycloak:keycloak-ldap-federationMaven	v < 26.6.3	26.6.3

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