Capsule: Malformed ForbiddenAnnotations.Regex can bypass Tenant validation and trigger namespace admission panic

Capsule is a multi-tenancy and policy-based framework for Kubernetes. From 0.13.0 until 0.13.7, the Tenant update validation in internal/webhook/tenant/validation/forbidden_annotations_regex.go compiles ForbiddenLabels.Regex for both the labels and annotations checks instead of validating ForbiddenAnnotations.Regex. An administrator who can update a Tenant can therefore persist a malformed ForbiddenAnnotations.Regex while leaving the labels expression valid. Namespace creation or update later passes the stored expression through pkg/api/forbidden_list.go, where regexp.MustCompile can panic during forbidden metadata validation and deny namespace operations for the affected tenant. This issue is fixed in version 0.13.7.

Source published

18 Sep 2026 16:26:18 UTC

Source modified

22 Sep 2026 14:55:27 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 6.8 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H