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

> Authenticated tenant users can inject labels into system namespaces, bypassing isolation and escalating privileges to access cross-tenant resources.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 Aug 2025
- **Updated:** 18 Aug 2025
- **Also known as:** GHSA-fcpm-6mxq-m5vv, GO-2025-3893

## What is CVE-2025-55205?

CVE-2025-55205 is a critical vulnerability in projectcapsule capsule, published on 18 Aug 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2025-55205?

3 open source packages ship an affected version, including github.com/projectcapsule/capsule.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.10.4 |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.10.4 |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.10.4 |

## How do I fix CVE-2025-55205?

Upgrade github.com/projectcapsule/capsule to 0.10.4 or later.

## Is CVE-2025-55205 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-55205 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-55205 and fix it if it is affected.

What it is: CVE-2025-55205 is a critical vulnerability in projectcapsule capsule, published on 18 Aug 2025. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-55205 exists.

Affected packages and fixed versions:
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.10.4
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.10.4
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.10.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-55205/ (Markdown: https://insights.sbomify.com/CVE-2025-55205/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-55205
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-55205
- OSV: https://osv.dev/vulnerability/CVE-2025-55205

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-55205/
Summaries are generated and may contain mistakes; the official description above is the record.