CVE-2025-11538 is a vulnerability identified in the Red Hat build of Keycloak version 26.4, specifically related to the insecure default binding behavior of the Java Debug Wire Protocol (JDWP) port when debug mode is enabled using the --debug <port> option. Normally, JDWP is used for debugging Java applications and should be restricted to localhost to prevent unauthorized access. However, in this case, enabling debug mode causes the JDWP port to bind to 0.0.0.0, meaning it listens on all network interfaces, exposing the debug port to any device on the same local network segment. This exposure allows an attacker with network access to connect remotely to the JDWP port without authentication and attach a debugger session to the Keycloak Java virtual machine. Through this remote debugging capability, an attacker can execute arbitrary code within the JVM process hosting Keycloak, potentially leading to full compromise of the server, including access to sensitive authentication and authorization data managed by Keycloak. The CVSS v3.1 base score is 6.8 (medium severity), reflecting that the attack vector is local network (AV:A), with high attack complexity (AC:H), no privileges required (PR:N), and no user interaction (UI:N). The impact on confidentiality and integrity is high, while availability is not affected. No known exploits have been reported in the wild yet. The vulnerability arises from a misconfiguration or insecure default in debug mode usage rather than a code flaw in Keycloak itself. Since Keycloak is widely used for identity and access management, this vulnerability poses a significant risk if debug mode is enabled in production or exposed network environments.

For European organizations, the impact of CVE-2025-11538 can be substantial, especially for those relying on Keycloak for critical identity and access management functions. Successful exploitation allows attackers on the same local network segment to execute arbitrary code within the Keycloak JVM, potentially leading to unauthorized access to authentication tokens, user credentials, and administrative controls. This can result in identity theft, privilege escalation, and lateral movement within enterprise networks. Confidentiality and integrity of authentication data are severely compromised, undermining trust in security controls. Although the attack requires local network access, many enterprise environments have segmented networks where internal threats or compromised devices could exploit this vulnerability. The lack of user interaction and authentication requirements lowers the barrier for attackers once network access is gained. Given the widespread use of Red Hat and Keycloak in European public and private sectors, the vulnerability could affect a broad range of organizations, including government agencies, financial institutions, and large enterprises. The absence of known exploits in the wild suggests limited immediate risk, but the potential for future exploitation remains high if mitigations are not applied promptly.

To mitigate CVE-2025-11538, organizations should first ensure that debug mode is disabled in all production Keycloak deployments, as it is primarily intended for development and troubleshooting purposes. If debug mode must be enabled, explicitly configure the JDWP port to bind only to localhost (127.0.0.1) rather than all network interfaces to prevent remote network access. Network-level controls such as firewall rules should be implemented to block access to the debug port from unauthorized hosts, restricting it to trusted administrators or isolated management networks. Monitoring and logging of debug port activity can help detect unauthorized access attempts. Organizations should track Red Hat advisories and apply any patches or updates addressing this vulnerability as soon as they become available. Additionally, conducting network segmentation and zero-trust principles can reduce the risk of attackers gaining local network access required for exploitation. Regular security audits and configuration reviews should verify that debug mode is not enabled unintentionally in production environments.