CVE-2024-5042 is a vulnerability identified in the Submariner project, an open-source tool designed to enable networking between Kubernetes clusters. The flaw arises from overly permissive role-based access control (RBAC) settings that grant unnecessary privileges to certain roles. Specifically, this misconfiguration allows a user or attacker with already high privileges to execute a malicious container on a node within the cluster. Once the malicious container is running, the attacker can steal service account tokens, which are credentials used by Kubernetes components and applications to authenticate and authorize actions within the cluster. With these tokens, the attacker can escalate their access, move laterally across nodes, and potentially compromise the entire cluster environment. The vulnerability affects versions from 0 up to 0.18.0-m0 of Submariner. The CVSS 3.1 score is 6.6, reflecting a medium severity level, 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) that impacts confidentiality (C:L) and integrity (I:H) but not availability (A:N). No public exploits have been reported yet, but the risk remains significant due to the potential for cluster-wide compromise. The root cause is the assignment of excessive RBAC permissions that are not strictly necessary for normal operation, which violates the principle of least privilege. This vulnerability highlights the critical importance of carefully scoping permissions in Kubernetes environments, especially in multi-cluster networking solutions like Submariner.

For European organizations, especially those leveraging Kubernetes clusters interconnected via Submariner, this vulnerability poses a significant risk to the confidentiality and integrity of their containerized workloads. An attacker exploiting this flaw could gain unauthorized access to service account tokens, enabling them to impersonate legitimate services and escalate privileges within the cluster. This can lead to data exfiltration, unauthorized modifications, and disruption of critical services. Organizations in sectors such as finance, healthcare, telecommunications, and critical infrastructure, which increasingly rely on container orchestration for scalability and resilience, could face operational disruptions and regulatory compliance issues if their clusters are compromised. The lateral movement capability increases the attack surface, potentially affecting multiple clusters and data centers. Given the interconnected nature of modern cloud-native environments, a successful exploit could also impact supply chain security and cross-border data flows, raising concerns under GDPR and other European data protection regulations.

To mitigate CVE-2024-5042, European organizations should immediately audit and tighten RBAC policies within their Submariner deployments, ensuring that no roles have more privileges than necessary. Specifically, review the permissions granted to users and service accounts that can deploy containers on cluster nodes, restricting them to the minimum required scope. Apply the principle of least privilege rigorously. Upgrade Submariner to a patched version once available; in the meantime, consider disabling or restricting features that allow container execution on nodes if feasible. Implement network segmentation and strict pod security policies to limit the ability of compromised containers to communicate laterally. Monitor Kubernetes audit logs and container runtime logs for unusual activity, such as unexpected container launches or token accesses. Employ runtime security tools that can detect anomalous behavior indicative of token theft or privilege escalation. Additionally, rotate service account tokens regularly and consider using short-lived tokens or bound tokens to reduce the window of exploitation. Finally, ensure that cluster nodes and control planes are hardened and that access to the Kubernetes API is tightly controlled and monitored.