Capsule: Incomplete fix of CVE-2026-30963: singular/plural typo leaves namespaces/finalize unprotected
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- Low · High · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-863.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| projectcapsule | capsule | 0.13.0 to before 0.13.6 | 0.13.6 | Patch available | CNA |
| — | github.com/projectcapsule/capsule (Go) | 0.13.0 to before 0.13.6 | 0.13.6 | Patch available | GHSA-gwxr-7h77-7777 |
- capsule Vendorprojectcapsule Affected 0.13.0 to before 0.13.6 Fixed in 0.13.6 Patch available CNA
- github.com/projectcapsule/capsule (Go) Vendor— Affected 0.13.0 to before 0.13.6 Fixed in 0.13.6 Patch available GHSA-gwxr-7h77-7777
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:projectcapsule:capsule:*:*:*:*:*:*:*:* | — | — | projectcapsule |
- cpe:2.3:a:projectcapsule:capsule:*:*:*:*:*:*:*:* Versions — — ·projectcapsule
Remediation
- Fix · CNA capsule (projectcapsule) Fixed in 0.13.6
- Fix · GHSA-gwxr-7h77-7777 github.com/projectcapsule/capsule (Go) Fixed in 0.13.6 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-55636
- 2026-10-03 Alias added: GHSA-gwxr-7h77-7777
References
Other 5
- https://github.com/projectcapsule/capsule/security/advisories/GHSA-gwxr-7h77-7777
- https://github.com/projectcapsule/capsule/pull/1966
- https://github.com/projectcapsule/capsule/commit/af2f37793e789b2301da8ed8dfb52ab60affebb6
- https://github.com/projectcapsule/capsule/releases/tag/v0.13.6
- https://github.com/projectcapsule/capsule
More projectcapsule vulnerabilities
- TI-2024-26614 Capsule tenant owner with "patch namespace" permission can hijack system namespaces CVSS 3.1HIGH 8.8
- TI-2025-34881 Capsule tenant owners with "patch namespace" permission can hijack system namespaces label CVSS 3.1CRITICAL 9.1
- TI-2026-18364 Capsule TenantResource RawItems Cluster-Scoped Resource Creation Vulnerability CVSS 4.0MEDIUM 6.9
- TI-2026-44157 Capsule: Tenant owner bypasses Capsule's forbidden namespace/service/node label and annotation enforcement CVSS 3.1HIGH 7.1
- TI-2026-46911 Improper input validation in projectcapsule capsule CVSS 3.1MEDIUM 6.8
- TI-2026-44232 Capsule: Malformed ForbiddenAnnotations.Regex can bypass Tenant validation and trigger namespace admission panic CVSS 3.1MEDIUM 6.8
Sources
- CVE-2026-55636 · CVE Program
- CVE-2026-55636 · NVD
- FIRST EPSS
- GHSA-gwxr-7h77-7777 · GitHub Advisory Database · CC BY 4.0
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