# CVE-2026-55636

## Summary

- **CVE ID:** CVE-2026-55636
- **Severity:** MEDIUM
- **CVSS Score:** 5.7 (CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:H/A:L)
- **CWE:** CWE-863
- **Published:** Sep 15, 2026
- **Last Modified:** Sep 15, 2026

## Description

Capsule is a multi-tenancy and policy-based framework for Kubernetes. From 0.13.0 until 0.13.6, charts/capsule/templates/configuration.yaml configures the validating webhook with namespace/finalize instead of the Kubernetes resource name namespaces/finalize. A user with namespaces/finalize RBAC can send a PUT request to /api/v1/namespaces/{namespace}/finalize, and the singular rule never matches the plural resource, so the validating webhook is not invoked and the user can change the namespace tenant label. matchPolicy: Equivalent does not compensate because it handles API group and version equivalence rather than resource-name errors. This vulnerability is fixed in 0.13.6.

## Affected Products

- projectcapsule — capsule (>= 0.13.0, < 0.13.6)

## References

- [CNA](https://github.com/projectcapsule/capsule/security/advisories/GHSA-gwxr-7h77-7777)
- [CNA](https://github.com/projectcapsule/capsule/pull/1966)
- [CNA](https://github.com/projectcapsule/capsule/commit/af2f37793e789b2301da8ed8dfb52ab60affebb6)
- [CNA](https://github.com/projectcapsule/capsule/releases/tag/v0.13.6)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.28%
- **EPSS Percentile:** 20.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._