Description
Capsule is a multi-tenancy and policy-based framework for Kubernetes. The Capsule Controller runs with cluster-admin privileges. Although the TenantResource RawItems processing logic forcibly sets the namespace, this is ineffective for cluster-scoped resources. Prior to version 0.13.0, tenant administrators can leverage the Controller's elevated privileges to create cluster-scoped resources (such as ClusterRole and ValidatingWebhookConfiguration) that they cannot create directly, achieving cross-tenant privilege escalation and cluster-level attacks. The attack vector has a few limiting factors. This attack requires Tenant Owner privileges and requires Capsule Controller running with cluster-admin privileges (default configuration). Additionally, some clusters may have additional admission controllers blocking malicious resources. Version 0.13.0 patches this issue.
Affected products
projectcapsule: capsule
References3
- github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm… ExploitVendor Advisory
- github.com/projectcapsule/capsule/security/advisories/GHSA-qjjm… ExploitVendor Advisory
- github.com/projectcapsule/capsule/releases/tag/v0.13.0 ProductRelease Notes
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H - CVSS 4.0
-
6.9
MEDIUM
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 53 · as of 15 November 2026
- CWE
- CWE-20CWE-863
Could this be exploited in your environment?
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