CVE-2024-5042 is a security vulnerability identified in the Submariner project, which facilitates multi-cluster networking for Kubernetes environments. The root cause is the assignment of unnecessary privileges through overly permissive role-based access control (RBAC) configurations. This misconfiguration allows an attacker who already has elevated privileges on a node to execute a malicious container. Once running, the attacker can exploit the container to steal service account tokens, which are credentials used by Kubernetes pods to authenticate with the API server. With stolen tokens, the attacker can escalate their access, potentially compromising other nodes and the entire Kubernetes cluster. The vulnerability affects Submariner versions 0 through 0.18.0-m0. The CVSS 3.1 score is 6.6 (medium severity), with the vector indicating network attack vector (AV:N), high attack complexity (AC:H), requiring high privileges (PR:H), no user interaction (UI:N), and a scope change (S:C). The impact on confidentiality is low (C:L), but integrity is high (I:H), and availability is not affected (A:N). No public exploits have been reported yet, but the vulnerability presents a significant risk in environments where attackers can gain privileged access to nodes. The flaw underscores the importance of the principle of least privilege in RBAC configurations within Kubernetes clusters and the need for careful control of container execution permissions.

For European organizations, especially those leveraging Kubernetes and Submariner for multi-cluster networking, this vulnerability poses a risk of cluster-wide compromise. Attackers with privileged node access could move laterally across clusters, steal sensitive credentials, and manipulate workloads, potentially leading to data breaches, service disruptions, and loss of integrity in critical applications. Given the increasing adoption of cloud-native technologies in Europe, the vulnerability could affect sectors such as finance, healthcare, and critical infrastructure where Kubernetes is used. The compromise of service account tokens could also facilitate further attacks on connected cloud services and internal networks. The medium severity score reflects the requirement for high privileges to exploit, but the potential scope of damage within a cluster is significant. Organizations failing to restrict RBAC permissions or monitor container deployments may face elevated risks.

1. Apply patches or updates from the Submariner project as soon as they become available to address the RBAC misconfigurations. 2. Conduct a thorough audit of RBAC roles and bindings within Kubernetes clusters to ensure the principle of least privilege is enforced, removing unnecessary permissions that allow container execution on nodes. 3. Implement strict admission controls and pod security policies to restrict which containers can run on nodes, especially limiting privileged containers. 4. Monitor Kubernetes audit logs and container runtime logs for anomalous container creation or execution activities that could indicate exploitation attempts. 5. Use network segmentation and node isolation to limit the impact of a compromised node. 6. Employ runtime security tools that can detect and block suspicious container behaviors. 7. Educate DevOps and security teams about the risks of excessive RBAC permissions and the importance of secure cluster configuration. 8. Regularly review and update cluster security policies as part of the organization's security posture management.