A high-severity vulnerability in the Kyverno policy engine allows authenticated users to leak sensitive service account tokens to external, attacker-controlled endpoints.

This is an insecure information storage issue (CWE-922) where the apiCall servicecall helper implicitly injects the Kyverno controller service account token into requests. Because the service URL is policy-controlled, an attacker with the ability to define ClusterPolicies can redirect this token to an arbitrary remote endpoint.

Successful exploitation allows an attacker to obtain the Kyverno controller service account token, which typically possesses high-level cluster privileges. Compromise of this token enables unauthorized access to the Kubernetes API, potentially leading to full cluster compromise, data exfiltration, or unauthorized configuration changes. With a CVSS score of 8.1, this vulnerability represents a significant risk to the integrity and confidentiality of cloud-native environments.

Immediate Action: Upgrade to Kyverno version 1.16.4 or later to ensure the service account token is no longer implicitly included in policy-controlled API calls.

Proactive Monitoring: Review existing ClusterPolicies for suspicious apiCall configurations and monitor egress traffic logs for unexpected connections originating from the Kyverno controller pod.

Compensating Controls: Implement strict NetworkPolicies to restrict the Kyverno controller pod from initiating outbound connections to untrusted or external IP addresses.

Public Exploit Available: Unknown.

The ability for a policy-controlled parameter to leak high-privilege credentials makes this vulnerability a critical concern for platform engineering teams. Administrators must prioritize updating the Kyverno controller immediately and auditing current ClusterPolicies to ensure no malicious or misconfigured policies are present in the cluster.