Kyverno CVE-2026-54523: Cross-Namespace Privilege Escalation via NamespacedMutatingPolicy

Kyverno Vulnerability Summary Vulnerability Overview Vulnerability Name: In v1.18.1, the parameter of in is not validated, enabling cross-namespace resource generation via the admission controller. CVE ID: CVE-2026-54523 Severity: Critical (CVSS v3.1 score 9.6) Affected Versions: v1.18.0, v1.18.1 Fixed Version: 1.18.2 Scope of Impact Only affects (v1.18.0 / v1.18.1). Namespace-level users with permissions can craft an admission controller by passing an arbitrary namespace string to the CEL , thereby generating resources (e.g., ConfigMap, Secret) in any namespace. The cluster-level privileges of the admission controller are leveraged to achieve privilege escalation. The affected attack surface includes: injecting cluster configurations into protected namespaces (e.g., , ), bypassing cluster networking via WebhookPolicies, and achieving privilege escalation via RoleBinding creation. Any deployment that allows non-admin users to create instances is affected. Root Cause The admission validator in only checks if the policy compiles; it fails to properly enforce namespace scoping for the parameters. accepts cross-namespace ConfigMap references; enforces namespace segment matching, but lacks corresponding safeguards. In v1.18.1, is not a vector due to incomplete wiring of webhook and background processing (unregistered or inactive). Remediation Upgrade to version 1.18.2. In , restrict the namespace scope via to prevent cross-namespace resource generation. PoC Code Prerequisites: The namespace contains ; the attacker can create a policy in : Trigger Mechanism: After applying this policy, create any ConfigMap within to trigger the admission webhook. The admission controller will then create in the namespace. By default, the admission controller holds permissions to create ConfigMaps in all namespaces.

Goal Reached Thanks to every supporter — we hit 100%!

Kyverno CVE-2026-54523: Cross-Namespace Privilege Escalation via NamespacedMutatingPolicy

More from this source