What’s Vulnerable › Vulnerabilities

CVE-2026-55636: Capsule: Incomplete fix of CVE-2026-30963: singular/plural typo leaves namespaces/finalize unprotected

• Severity: medium (CVSS 5.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-15 · updated 2026-09-30
• Weakness: CWE-863

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: from 0.13.0, < 0.13.6

References

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

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