Kubewarden: RBAC Reconnaissance via unchecked can_i host capability call

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Kubewarden is a policy engine for Kubernetes. Prior to , 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. can_i does not perform that check to enforce the context-aware allow-list 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. This vulnerability is fixed in .

Source published

12 May 2026 17:57:54 UTC

Source modified

14 May 2026 12:23:15 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Kubewarden is a policy engine for Kubernetes. Prior to , 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. can_i does not perform that check to enforce the context-aware allow-list 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. This vulnerability is fixed in .

Source published

May 12, 2026, 5:57:54 PM (timezone not stated)

Source modified

May 14, 2026, 12:23:15 PM (timezone not stated)

Observed here

7 Nov 2026 09:35:10 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Kubewarden is a policy engine for Kubernetes. Prior to , 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. can_i does not perform that check to enforce the context-aware allow-list 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. This vulnerability is fixed in .

Source published

12 May 2026 18:17:24 UTC

Source modified

26 Oct 2026 18:10:00 UTC

Observed here

27 Oct 2026 11:12:04 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · [email protected] · Secondary · 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

### Impact 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. ### Patches 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](https://artifacthub.io/packages/kubewarden/kubewarden-policy-library/ns-policyserver-mapper) policy, their own policy or other means, such as GitOps. See: https://docs.kubewarden.io/howtos/policy-servers/namespaced-policies-capabilities ### 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

Source published

5 May 2026 21:49:03 UTC

Source modified

25 Jun 2026 23:11:10 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Publisher rating · MODERATE

Kubewarden vulnerable to RBAC Reconnaissance via unchecked can_i host capability call in github.com/kubewarden/kubewarden-controller

Source published

25 Jun 2026 22:34:38 UTC

Source modified

25 Jun 2026 23:01:42 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.