CVE-2026-61672 Capsule: Tenant owner bypasses Capsule's forbidden namespace/service/node label and annotation enforcement
Tenant owners can bypass Capsule's forbidden label and annotation enforcement due to a sorting bug, allowing them to violate cluster policies and tenant boundaries.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-61672?
CVE-2026-61672 is a high-severity vulnerability in projectcapsule capsule, published on 18 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Capsule is a multi-tenancy and policy-based framework for Kubernetes. Prior to 0.13.7, ForbiddenListSpec.ExactMatch in pkg/api/forbidden_list.go sorts denied metadata keys case-insensitively and then uses sort.SearchStrings, which assumes byte-order sorting. When an administrator's forbidden list mixes capitalized and lowercase keys or otherwise has different case-insensitive and byte ordering, the binary search can return false for a key that is present. An authenticated tenant owner can then pass the missed key through api.ValidateForbidden and bypass configured namespace, Service, or delegated node metadata restrictions, potentially influencing cluster policies, network exposure, or scheduling outside the tenant boundary. Uniformly lowercase lists whose two orderings coincide are not affected. This issue is fixed in version 0.13.7.
Which versions are affected by CVE-2026-61672?
3 open source packages ship an affected version, including github.com/projectcapsule/capsule.
| Package | Affected | Fixed in |
|---|---|---|
github.com/projectcapsule/capsule Go | All versions | 0.13.7 |
github.com/projectcapsule/capsule Go | All versions | 0.13.7 |
github.com/projectcapsule/capsule Go | All versions | 0.13.7 |
How do I fix CVE-2026-61672?
Upgrade github.com/projectcapsule/capsule to 0.13.7 or later.
Is CVE-2026-61672 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61672 exists.
Sources
Also known as GHSA-gjw4-3v3v-rqxg, GO-2026-6520.