CVE-2025-13467 is a deserialization vulnerability found in the LDAP User Federation provider component of the Red Hat build of Keycloak version 26.2.11. Keycloak is an open-source identity and access management solution widely used for single sign-on and user federation. The vulnerability arises because the LDAP User Federation provider improperly handles Java object deserialization when connecting to an LDAP server. An authenticated realm administrator can configure the LDAP server settings to point to a malicious LDAP server that returns crafted serialized Java objects. When Keycloak deserializes these objects without sufficient validation, it can lead to execution of untrusted code or manipulation of internal state. The attack vector requires network access and realm admin privileges, but no user interaction is needed. The vulnerability impacts confidentiality and integrity by potentially exposing sensitive data or allowing unauthorized changes within the Keycloak realm. Availability is not affected. The CVSS 3.1 score of 5.5 reflects the medium severity, considering the required privileges and the limited scope of impact. No public exploits or patches are currently reported, but the flaw is documented and should be addressed promptly. This vulnerability highlights the risks of deserialization attacks in Java applications, especially in identity management systems that integrate external services like LDAP.

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality and integrity of identity and access management data. Keycloak is often used in enterprise environments to centralize authentication and authorization, so exploitation could allow attackers with realm admin credentials to manipulate user data, escalate privileges, or exfiltrate sensitive information. While availability is not impacted, the compromise of identity management systems can have cascading effects on other connected applications and services. Organizations relying on LDAP integration with Keycloak are particularly vulnerable if administrators are tricked or coerced into configuring malicious LDAP servers. The threat is heightened in sectors with stringent compliance requirements such as finance, healthcare, and government, where identity data integrity is critical. The absence of known exploits reduces immediate risk, but the medium severity and ease of exploitation by privileged users necessitate proactive mitigation to prevent insider threats or targeted attacks.

1. Restrict realm administrator privileges strictly to trusted personnel and enforce strong authentication and authorization controls. 2. Implement rigorous validation and verification of LDAP server configurations before applying them in Keycloak to prevent malicious endpoints. 3. Monitor and audit changes to LDAP federation settings and realm configurations to detect suspicious activities promptly. 4. Apply vendor patches or updates as soon as they become available from Red Hat to remediate the vulnerability. 5. Consider isolating Keycloak administrative interfaces within secure network segments to limit exposure. 6. Employ runtime application self-protection (RASP) or Java deserialization security libraries to detect or block unsafe deserialization attempts. 7. Conduct regular security training for administrators on the risks of configuring external services and recognizing potential social engineering attacks. 8. Review and harden Java security policies related to deserialization in the Keycloak deployment environment.