# 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.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-gxjc-74v5-3vx3, GO-2026-6521

## 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 (Improper Input Validation)

## Which versions are affected by CVE-2026-61794?

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


| Package | Ecosystem | 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.

## Is CVE-2026-61794 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61794 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-61794 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61794 exists.

Affected packages and fixed versions:
- github.com/projectcapsule/capsule (Go): affected from 0.13.0; fixed in 0.13.7
- github.com/projectcapsule/capsule (Go): affected from 0.13.0; fixed in 0.13.7
- github.com/projectcapsule/capsule (Go): affected from 0.13.0; fixed in 0.13.7

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-2026-61794/ (Markdown: https://insights.sbomify.com/CVE-2026-61794/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61794
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61794
- OSV: https://osv.dev/vulnerability/CVE-2026-61794

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-61794/
Summaries are generated and may contain mistakes; the official description above is the record.