Executive brief
Kyverno is a policy engine for Kubernetes that validates and enforces rules on cluster resources. A low-privilege user can bypass namespace isolation checks by using percent-encoded path segments in policy API calls, allowing them to read resources from other namespaces using the Kyverno controller's administrative credentials. This could expose sensitive data like configuration files and secrets across the entire cluster without proper access controls.
Technical details
The vulnerability exists in the apiCall context entry of namespaced Policy resources, where the namespace isolation check performs lexical path normalization via path.Clean() that does not percent-decode, while the actual API request execution uses url.Parse() which does percent-decode. An attacker can craft a path like /api/v1/namespaces/policy-ns/%2e%2e/victim-ns/configmaps/name to bypass the regex check and traverse to other namespaces. The request executes with the Kyverno admission controller's ServiceAccount privileges, not the requesting user's identity.
Affected products
- Kyverno Kyverno before 1.19.1
Timeline
- 2026-09-26: disclosed