Auth bypass in Projectcapsule Capsule
CVE-2026-55636
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.
Vulnerability class: Broken Access Control
CVSS v3 metric
CVSS v3 base score 5.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:H/A:L.
Affected products
- Projectcapsule Capsule — versions >= 0.13.0, < 0.13.6
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-55636?
- CVE-2026-55636 is a medium-severity vulnerability in Projectcapsule Capsule, classified under Incorrect Authorization. CVSS score: 5.7/10. Published 2026-09-15.
- How severe is CVE-2026-55636?
- Medium severity. CVSS v3 base score is 5.7 out of 10.