Executive brief
Kyverno is a policy engine that validates and enforces rules on Kubernetes clusters. The apiCall feature automatically attaches the Kubernetes ServiceAccount token (a sensitive credential) to HTTP requests sent to external or attacker-controlled endpoints without explicit authorization. An attacker who controls a destination endpoint or can redirect traffic can steal this token and gain full administrative control over Kyverno policies and cluster resources.
Technical details
The vulnerability is a credential exposure flaw (CWE-200, CWE-522) in Kyverno's apiCall executor (pkg/engine/apicall/executor.go). When an apiCall policy rule lacks an explicit Authorization header, the code automatically reads the admission controller's ServiceAccount token from /var/run/secrets/kubernetes.io/serviceaccount/token and injects it as "Authorization: Bearer <token>" into every outbound HTTP request. The root cause is implicit credential forwarding without trust boundary validation or documentation. An attacker can exfiltrate the token by directing apiCall requests to external endpoints or performing request interception. The exposed token grants full control over Kyverno policies, the ability to create/delete webhooks, and read cluster-wide resources, enabling privilege escalation and persistence. Patch: upgrade to Kyverno 1.16.4 or later.
Affected products
- Kyverno Kyverno before 1.16.4
Timeline
- 2026-04-15: disclosed: GitHub Security Advisory (GHSA-8wfp-579w-6r25) published
- 2026-04-15: patched: Version 1.16.4 released with fix
- 2026-09-01: advisory: CVE-2026-84195 assigned and published on NVD