Overview
CVE-2025-11538 is a security vulnerability affecting Keycloak, a popular open-source identity and access management solution. This vulnerability arises when Keycloak’s debug mode is enabled without proper configuration. Specifically, the issue stems from the Java Debug Wire Protocol (JDWP) port binding to all network interfaces (0.0.0.0) by default when the --debug <port> flag is used. This default behavior exposes the debug port, potentially allowing unauthorized remote code execution.
Technical Details
The vulnerability lies in the insecure default configuration of the debug mode. When initiated with the --debug <port> flag, Keycloak binds the JDWP port to all available network interfaces. This means that anyone on the same network segment as the Keycloak server can potentially connect to the debug port. An attacker can then attach a remote debugger and execute arbitrary code within the context of the Keycloak Java Virtual Machine (JVM). The JDWP protocol is designed for debugging purposes and lacks built-in authentication or encryption in its default configuration, making it an attractive target for exploitation.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2025-11538 is 6.8 (Medium).
- Attack Vector (AV): A (Adjacent Network)
- Attack Complexity (AC): L (Low)
- Privileges Required (PR): N (None)
- User Interaction (UI): N (None)
- Scope (S): U (Unchanged)
- Confidentiality Impact (C): H (High)
- Integrity Impact (I): H (High)
- Availability Impact (A): H (High)
This score indicates that an attacker on the same network segment can easily exploit the vulnerability without requiring any privileges or user interaction. Successful exploitation can lead to complete compromise of the Keycloak server.
Possible Impact
Exploitation of CVE-2025-11538 can have severe consequences:
- Remote Code Execution: The most critical impact is the ability for an attacker to execute arbitrary code on the Keycloak server. This can lead to complete system compromise.
- Data Breach: An attacker can access and steal sensitive data stored within Keycloak, including user credentials, configuration settings, and potentially application data protected by Keycloak.
- Service Disruption: The attacker can disrupt the availability of the Keycloak service, preventing users from authenticating or accessing applications.
- Privilege Escalation: Even if the Keycloak process is running with limited privileges, the attacker might be able to escalate privileges and gain full control of the underlying operating system.
Mitigation or Patch Steps
To mitigate the risk associated with CVE-2025-11538, consider the following steps:
- Avoid using the –debug flag in production: The debug mode should only be enabled in development or testing environments.
- Bind JDWP to a specific IP address: If debug mode is necessary, configure the JDWP port to bind to a specific, non-public IP address (e.g., 127.0.0.1) using the
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=127.0.0.1:<port>JVM argument. This restricts access to the debug port to only the local machine. - Use a secure tunnel: If remote debugging is required, establish a secure tunnel (e.g., SSH tunnel) between your local machine and the Keycloak server to encrypt the JDWP traffic and restrict access.
- Apply Security Patches: Upgrade to the latest version of Keycloak that includes security patches addressing this vulnerability. Refer to the vendor’s security advisories for specific patch information.
- Network Segmentation: Isolate the Keycloak server within a segmented network to limit the impact of a potential breach.
