Kyverno Policy Engine Flaw Leaks Service Account Tokens

The National Vulnerability Database has disclosed CVE-2026-40868, a high-severity vulnerability (CVSS 8.1) in Kyverno, a policy engine for cloud-native environments. Prior to version 1.16.4, Kyverno’s apiCall servicecall helper implicitly injected the Kyverno controller service account token into API calls when an explicit Authorization header was absent.

This flaw means that if a ClusterPolicy or global context policy used context.apiCall.service.url without specifying an Authorization header, the Kyverno service account token could be inadvertently sent to an attacker-controlled endpoint. This constitutes a confused deputy scenario, where Kyverno acts on behalf of an attacker due to its implicit trust. The vulnerability is mitigated in Kyverno version 1.16.4.

This isn’t just a theoretical bug; it’s a critical logic bypass. An attacker leveraging this could gain unauthorized access or elevate privileges within the Kubernetes cluster by tricking Kyverno into authenticating to their malicious service. Defenders need to understand the implications of default behaviors and how they can be weaponized in cloud-native settings.