CVE-2026-42541

Workarounds

Cluster Operators can opt for:

• Not allowing users to create namespaced policies (AdmissionPolicies, AdmissionPolicyGroups).
• Removing SubjectAccessReview "create" permissions for the PolicyServer ServiceAccount RBAC being used, in custom PolicyServers and the PolicyServer default.

Resources

• Code changes, with new security feature: https://github.com/kubewarden/kubewarden-controller/pull/1693
• Documentation changes: https://github.com/kubewarden/docs/pull/737
  • Explained new feature on 1.35.0
  • Updated Threat model assessment

Kubewarden is a policy engine for Kubernetes. Kubewarden cluster operators can grant permissions to users to deploy namespaced AdmissionPolicies and AdmissionPolicyGroups in their Namespaces. One of Kubewarden promises is that configured users can deploy namespaced policies in a safe manner, without privilege escalation.

An attacker with privileged AdmissionPolicy or AdmissionPolicyGroup create permissions (which isn't the default) can craft a policy that makes use of the can_i host callback. The callback issues a SubjectAccessReview (SAR) requests to enumerate RBAC permissions of any user or service account across the cluster. Three operations on the host capabilities kubewarden/kubernetes binding enforce the context-aware allow-list via can_access_kubernetes_resource():

• list_resources_by_namespace
• list_resources_all
• get_resource

However, can_i does not perform that check and forwards the request directly to the callback handler, which executes a real SubjectAccessReview using policy-server privileges. This creates a policy-level authorization gap: can_i is effectively usable even when the policy has no context-aware resource grant.

This is an information disclosure / reconnaissance issue, and not direct workload data exfiltration. The attacker learns permission information, such as whether specific service accounts can "get secrets", "create pods", or "bind clusterroles" in chosen namespaces.

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

CVE-2026-42541 has a CVSS score of 4.3 (Medium). 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 (1.35.0); upgrading removes the vulnerable code path.

Kodem intelligence

Cluster Operators, if providing their users with privileges to deploy AdmissionPolicies or AdmissionPolicygroups (which isn't the default), must then also deploy PolicyServers with reduced permissions for host capability calls. This includes the PolicyServer default.
For that, make use of the new feature in v1.35:

• For custom PolicyServers: Set the new PolicyServer.spec.namespacedPoliciesCapabilities , for example to an empty list [] which doesn't allow any capability.
• For the default PolicyServer, set the .Values.policyServer.namespacedPoliciesCapabilities , for example to an empty list [] which doesn't allow any capability.

Also, if needed, they must ensure that those namespaced AdmissionPolicies or AdmissionPolicygroups are scheduled in the PolicyServers with reduced permissions.
For that, they could make use of the new ns-policyserver-mapper policy, their own policy or other means, such as GitOps.

See: https://docs.kubewarden.io/howtos/policy-servers/namespaced-policies-capabilities

1. What is CVE-2026-42541? CVE-2026-42541 is a medium-severity missing authorization vulnerability in github.com/kubewarden/kubewarden-controller (go), affecting versions < 1.35.0. It is fixed in 1.35.0. The application does not perform an authorization check before performing a sensitive operation.
2. How severe is CVE-2026-42541? CVE-2026-42541 has a CVSS score of 4.3 (Medium). 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/kubewarden/kubewarden-controller are affected by CVE-2026-42541? github.com/kubewarden/kubewarden-controller (go) versions < 1.35.0 is affected.
4. Is there a fix for CVE-2026-42541? Yes. CVE-2026-42541 is fixed in 1.35.0. Upgrade to this version or later.
5. Is CVE-2026-42541 exploitable, and should I be worried? Whether CVE-2026-42541 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-2026-42541 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-2026-42541? Upgrade github.com/kubewarden/kubewarden-controller to 1.35.0 or later.