Vulnerability · Published Jun 1, 2026 · Assigned by GitHub_M
CVE-2026-30963Capsule Namespace Hijacking via subresource
Low 3.9
In plain English
A low-severity improper input validation in capsule from projectcapsule. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 12% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Go | github.com/projectcapsule/capsule | 0.13.0 | GHSA-2ww6-hf35-mfjm |
| Go | github.com/projectcapsule/capsule | 0.13.0 | GO-2026-5043 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| projectcapsule | capsule | < 0.13.0 |
Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:L
References
- https://github.com/projectcapsule/capsule/security/advisories/GHSA-2ww6-hf35-mfjm x_refsource_CONFIRM
- https://github.com/projectcapsule/capsule/releases/tag/v0.13.0 x_refsource_MISC