A critical security flaw in Kyverno allows authenticated users to leak sensitive service account tokens via SSRF, resulting in a risk of full Kubernetes cluster compromise.

This vulnerability involves a combination of Server-Side Request Forgery (CWE-918) and sensitive information exposure (CWE-200). An authenticated user with sufficient permissions to define a ClusterPolicy can trigger outgoing HTTP requests to attacker-controlled endpoints, causing the admission controller to automatically leak its ServiceAccount token.

The exploitation of this vulnerability poses a severe threat to containerized environments. Because the leaked ServiceAccount token possesses high-level permissions, including the ability to patch webhook configurations, an attacker could escalate privileges to achieve full control over the Kubernetes cluster. With a CVSS score of 8.1, this represents a High severity risk that could lead to unauthorized data access, lateral movement, and total system compromise.

Immediate Action: Upgrade to version 1.16.4, 1.17.2-rc1, or 1.18.0-rc1 immediately to include the necessary service URL validation logic.

Proactive Monitoring: Review cluster audit logs for unusual egress traffic originating from the Kyverno admission controller pod to unknown or external IP addresses.

Compensating Controls: Implement network policies that restrict the egress traffic of the Kyverno admission controller namespace to prevent unauthorized connections to external servers.

Public Exploit Available: Unknown

Given the potential for full cluster compromise, organizations utilizing Kyverno must prioritize this update. Administrators should verify their current deployment version and apply the vendor-provided patches as soon as possible to prevent the exposure of sensitive admission controller tokens.