# CVE-2026-65834: Capsule: CapsuleConfiguration NodeMetadata regex fields lack webhook validation, allowing MustCompile panic on all Node admission requests

> A Cluster Admin can cause a denial of service in the node admission webhook by storing malformed regex patterns in Capsule configuration.

- **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:** 30 Jul 2026
- **Updated:** 31 Jul 2026
- **Also known as:** GHSA-68cj-mvg9-rgm2, GO-2026-6155

## What is CVE-2026-65834?

CVE-2026-65834 is a medium-severity denial of service vulnerability in projectcapsule capsule, published on 30 Jul 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. Prior to 0.13.8, CapsuleConfiguration.Spec.NodeMetadata.ForbiddenLabels.Regex and CapsuleConfiguration.Spec.NodeMetadata.ForbiddenAnnotations.Regex were not validated by the configuration admission webhook, allowing a Cluster Admin to store a malformed regex that later reached regexp.MustCompile in pkg/api/forbidden_list.go through internal/webhook/node/user_metadata.go and crashed the node admission webhook on Node create, update, or patch requests. This issue is fixed in version 0.13.8.

Weakness: CWE-248 (Uncaught Exception), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-65834?

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 | 0.13.8 |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.13.8 |
| `github.com/projectcapsule/capsule` | Go | All versions | 0.13.8 |

## How do I fix CVE-2026-65834?

Upgrade github.com/projectcapsule/capsule to 0.13.8 or later.

## Is CVE-2026-65834 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-65834 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-65834 and fix it if it is affected.

What it is: CVE-2026-65834 is a medium-severity denial of service vulnerability in projectcapsule capsule, published on 30 Jul 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-2026-65834 exists.

Affected packages and fixed versions:
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.13.8
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.13.8
- github.com/projectcapsule/capsule (Go): affected all versions; fixed in 0.13.8

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-2026-65834/ (Markdown: https://insights.sbomify.com/CVE-2026-65834/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-65834
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-65834
- OSV: https://osv.dev/vulnerability/CVE-2026-65834

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-65834/
Summaries are generated and may contain mistakes; the official description above is the record.