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.
- 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
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
Which versions are affected by CVE-2025-55205?
3 open source packages ship an affected version, including github.com/projectcapsule/capsule.
| Package | 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.
Sources
Also known as GHSA-fcpm-6mxq-m5vv, GO-2025-3893.