CVE-2026-61794 Capsule: Malformed ForbiddenAnnotations.Regex can bypass Tenant validation and trigger namespace admission panic
An administrator can cause a panic in namespace admission by persisting a malformed regex, denying namespace operations for the affected tenant.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-61794?
CVE-2026-61794 is a medium-severity denial of service vulnerability in projectcapsule capsule, published on 18 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Capsule is a multi-tenancy and policy-based framework for Kubernetes. From 0.13.0 until 0.13.7, the Tenant update validation in internal/webhook/tenant/validation/forbidden_annotations_regex.go compiles ForbiddenLabels.Regex for both the labels and annotations checks instead of validating ForbiddenAnnotations.Regex. An administrator who can update a Tenant can therefore persist a malformed ForbiddenAnnotations.Regex while leaving the labels expression valid. Namespace creation or update later passes the stored expression through pkg/api/forbidden_list.go, where regexp.MustCompile can panic during forbidden metadata validation and deny namespace operations for the affected tenant. This issue is fixed in version 0.13.7.
Weakness: CWE-20
Which versions are affected by CVE-2026-61794?
3 open source packages ship an affected version, including github.com/projectcapsule/capsule.
| Package | Affected | Fixed in |
|---|---|---|
github.com/projectcapsule/capsule Go | From 0.13.0 | 0.13.7 |
github.com/projectcapsule/capsule Go | From 0.13.0 | 0.13.7 |
github.com/projectcapsule/capsule Go | From 0.13.0 | 0.13.7 |
How do I fix CVE-2026-61794?
Upgrade github.com/projectcapsule/capsule to 0.13.7 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-61794 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61794 exists.
Sources
Also known as GHSA-gxjc-74v5-3vx3, GO-2026-6521.