CVE-2026-30963 PUBLISHED

Capsule Namespace Hijacking via subresource

Assigner: GitHub_M
Reserved: 07.03.2026 Published: 01.06.2026 Updated: 02.06.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L
CVSS Score: 3.9

Product Status

Vendor projectcapsule
Product capsule
Versions
  • Version < 0.13.0 is affected

References

Problem Types

  • CWE-20: Improper Input Validation CWE