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.
Problem types
CWE-20: Improper Input Validation
Product status
References
github.com/...apsule/security/advisories/GHSA-2ww6-hf35-mfjm
github.com/...apsule/security/advisories/GHSA-2ww6-hf35-mfjm
github.com/projectcapsule/capsule/releases/tag/v0.13.0