---
title: "CVE-2025-55205: Capsule tenant owners with \"patch namespace\" permission can hijack system namespaces label"
url: https://erroneo.us/security/cve/CVE-2025-55205/
description: "CVE-2025-55205 (github.com/projectcapsule/capsule (Go)): Capsule is a multi-tenancy and policy-based framework for Kubernetes. A namespace label injection…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-08-18
date_modified: 2025-08-29
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-55205"
kev: false
cvss: 9.1
epss: 0.0046
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.5% , percentile 39: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 39% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes github.com/projectcapsule/capsule (Go) < 0.10.4, fixed in 0.10.4 . Check your lockfile, including transitive dependencies.

## What it is

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.

## Affected packages

- Go `github.com/projectcapsule/capsule` < 0.10.4 → fixed: 0.10.4

## Affected products (CVE record)

- projectcapsule capsule: < 0.10.4

## Severity

- GitHub_M CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.0 `CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.46% probability of exploitation activity in the next 30 days; percentile 39.

## Sources

- [GitHub Advisory GHSA-fcpm-6mxq-m5vv](https://github.com/advisories/GHSA-fcpm-6mxq-m5vv)
- [CVE.org record CVE-2025-55205](https://www.cve.org/CVERecord?id=CVE-2025-55205)
- [NVD entry CVE-2025-55205](https://nvd.nist.gov/vuln/detail/CVE-2025-55205)
- [github.com](https://github.com/projectcapsule/capsule/security/advisories/GHSA-fcpm-6mxq-m5vv)
- [github.com](https://github.com/projectcapsule/capsule/commit/e1f47feade6e1695b2204407607d07c3b3994f6e)
- [pkg.go.dev](https://pkg.go.dev/vuln/GO-2025-3893)

---
Source page: https://erroneo.us/security/cve/CVE-2025-55205/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt