CVE-2026-30963

/// Technical description

Capsule is a multi-tenancy and policy-based framework for Kubernetes. To defend against namespace hijacking achieved through update/patch operations on namespaces, Capsule uses a webhook to validate update requests targeting namespaces. However, in Kubernetes, the namespace/finalize and namespace/status subresource APIs can also modify various fields of a namespace, including the metadata field. Prior to version 0.13.0, the webhook does not define interception rules for these subresources. As a result, if a tenant administrator has permission to modify namespace/status or namespace/finalize, they can successfully perform namespace hijacking. Version 0.13.0 fixes the issue. Another mitigation is to add two subresources (namespaces and snamespaces/status with namespace/finalize within it) to the resources list in the ValidatingWebhookConfiguration rules.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References