CVE-2024-10973 is a vulnerability identified in Keycloak, an open-source identity and access management solution widely used for authentication and authorization services. The issue arises because the environment variable KC_CACHE_EMBEDDED_MTLS_ENABLED, which is supposed to enable mutual TLS (mTLS) encryption for JGroups replication traffic, does not function as intended. Consequently, the JGroups replication configuration defaults to transmitting data in plaintext. JGroups is a toolkit used by Keycloak for cluster communication and replication of cache data between nodes. This plaintext transmission exposes sensitive information to any attacker who can access the adjacent network segments where JGroups communication occurs. The vulnerability requires the attacker to have access to the network adjacent to the Keycloak cluster nodes but only low privileges on the system, and no user interaction is needed to exploit it. The CVSS 3.1 score is 5.7 (medium), reflecting the high confidentiality impact but no impact on integrity or availability. This flaw could lead to leakage of sensitive authentication tokens, session data, or other confidential information replicated between cluster nodes, potentially facilitating further attacks or unauthorized access. No patches or exploits are currently reported, but the vulnerability is publicly disclosed, increasing the risk of exploitation. Organizations using Keycloak in clustered deployments should be aware of this risk, especially if network segmentation is insufficient to isolate JGroups traffic.

For European organizations, the primary impact of CVE-2024-10973 is the potential exposure of sensitive authentication and session data transmitted between Keycloak cluster nodes. This can lead to confidentiality breaches, enabling attackers to capture tokens or credentials that could be used to impersonate users or escalate privileges. Organizations relying on Keycloak for critical identity management, especially in sectors like finance, healthcare, and government, face increased risk of data leakage and compliance violations under GDPR. The vulnerability does not affect data integrity or availability directly but can facilitate further attacks that compromise system security. The requirement for adjacent network access means that organizations with weak network segmentation or flat network architectures are particularly vulnerable. This risk is heightened in multi-tenant or cloud environments where network boundaries may be less controlled. The absence of known exploits currently provides a window for mitigation, but the public disclosure raises the likelihood of future exploitation attempts.

1. Monitor Keycloak vendor communications and apply official patches or updates promptly once available to fix the KC_CACHE_EMBEDDED_MTLS_ENABLED functionality. 2. Until patches are released, enforce strict network segmentation and isolation of Keycloak cluster nodes to prevent unauthorized access to JGroups communication channels. 3. Use network-level encryption such as VPNs or IPsec tunnels to protect inter-node communication if possible. 4. Audit and restrict network access controls to limit which hosts can reach the Keycloak cluster replication ports. 5. Implement network monitoring and intrusion detection systems to detect unusual traffic patterns or unauthorized access attempts on JGroups ports. 6. Review Keycloak cluster configurations to ensure no unnecessary exposure of replication traffic to untrusted networks. 7. Consider temporary disabling clustering or replication if feasible and if the risk outweighs operational needs until a fix is applied. 8. Educate administrators about the vulnerability and the importance of securing internal cluster communications.