Vulnerability-Lookup

CVE-2026-42541 (GCVE-0-2026-42541)

Vulnerability from cvelistv5 – Published: 2026-05-12 17:57 – Updated: 2026-05-14 12:23

Title

Kubewarden: RBAC Reconnaissance via unchecked can_i host capability call

Summary

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 .

Severity

4.3 (Medium)


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

CWE

CWE-862 - Missing Authorization

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/kubewarden/adm-controller/secu…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
kubewarden	kubewarden-controller	Affected: < 1.35.0

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-42541

Vulnerability from fkie_nvd - Published: 2026-05-12 18:17 - Updated: 2026-05-13 18:24

Severity

4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/kubewarden/adm-controller/security/advisories/GHSA-wqcw-g35j-j578

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Kubewarden is a policy engine for Kubernetes. Prior to , An attacker with privileged AdmissionPolicy or AdmissionPolicyGroup create permissions (which isn\u0027t 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 ."
    }
  ],
  "id": "CVE-2026-42541",
  "lastModified": "2026-05-13T18:24:31.310",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
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          "baseScore": 4.3,
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          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
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          "version": "3.1"
        },
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        "impactScore": 1.4,
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        "type": "Secondary"
      }
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  "published": "2026-05-12T18:17:24.957",
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GHSA-WQCW-G35J-J578

Vulnerability from github – Published: 2026-05-05 21:49 – Updated: 2026-05-13 16:27

Summary

Kubewarden vulnerable to RBAC Reconnaissance via unchecked can_i host capability call

Details

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 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

Severity

4.3 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/kubewarden/kubewarden-controller"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.35.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42541"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-05T21:49:03Z",
    "nvd_published_at": "2026-05-12T18:17:24Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\nKubewarden 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.\n\nAn attacker with privileged AdmissionPolicy or AdmissionPolicyGroup create permissions (which isn\u0027t 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()`:\n\n- `list_resources_by_namespace`\n- `list_resources_all`\n- `get_resource`\n\nHowever, `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.\n\nThis 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.\n\n### Patches\n\nCluster Operators, if providing their users with privileges to deploy AdmissionPolicies or AdmissionPolicygroups (which isn\u0027t the default), must then also deploy PolicyServers with reduced permissions for host capability calls. This includes the PolicyServer `default`. \nFor that, make use of the new feature in v1.35:\n- For custom PolicyServers: Set the new `PolicyServer.spec.namespacedPoliciesCapabilities` , for example to an empty list `[]` which doesn\u0027t allow any capability.\n- For the `default` PolicyServer, set the `.Values.policyServer.namespacedPoliciesCapabilities` , for example to an empty list `[]` which doesn\u0027t allow any capability. \n\nAlso, if needed, they must ensure that those namespaced AdmissionPolicies or AdmissionPolicygroups are scheduled in the PolicyServers with reduced permissions.\nFor 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.\n\nSee: https://docs.kubewarden.io/howtos/policy-servers/namespaced-policies-capabilities\n\n### Workarounds\n\nCluster Operators can opt for:\n- Not allowing users to create namespaced policies (AdmissionPolicies, AdmissionPolicyGroups).\n- Removing SubjectAccessReview \"create\" permissions for the PolicyServer ServiceAccount RBAC being used, in custom PolicyServers and the  PolicyServer `default`.\n\n### Resources\n\n- Code changes, with new security feature: https://github.com/kubewarden/kubewarden-controller/pull/1693\n- Documentation changes: https://github.com/kubewarden/docs/pull/737\n  - Explained new feature on 1.35.0\n  - Updated Threat model assessment",
  "id": "GHSA-wqcw-g35j-j578",
  "modified": "2026-05-13T16:27:04Z",
  "published": "2026-05-05T21:49:03Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/kubewarden/adm-controller/security/advisories/GHSA-wqcw-g35j-j578"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kubewarden/kubewarden-controller/security/advisories/GHSA-wqcw-g35j-j578"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42541"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kubewarden/docs/pull/737"
    },
    {
      "type": "WEB",
      "url": "https://github.com/kubewarden/kubewarden-controller/pull/1693"
    },
    {
      "type": "WEB",
      "url": "https://docs.kubewarden.io/howtos/policy-servers/namespaced-policies-capabilities"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/kubewarden/kubewarden-controller"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Kubewarden vulnerable to RBAC Reconnaissance via unchecked can_i host capability call"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-42541 (GCVE-0-2026-42541)

FKIE_CVE-2026-42541

GHSA-WQCW-G35J-J578

Impact

Patches

Workarounds

Resources

Tags

Sightings

Nomenclature