# CVE-2026-65834: Project Capsule Denial of Service via malformed NodeMetadata regex

Source: https://junglewise.ai/threats/cve-2026-65834-project-capsule-denial-of-service-via-malformed-nodemetadata  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-30. Updated: 2026-07-31  
License: CC BY 4.0 with a link back

CVE-2026-65834 · Severity: medium · CVSS 6.8 · Published 2026-07-30

Capsule is a tool used to manage multi-tenancy in Kubernetes clusters. A vulnerability exists where a cluster administrator can provide a malformed regular expression in the configuration settings, which causes the system to crash whenever any node in the cluster is updated or created. This results in a cluster-wide denial of service, preventing new nodes from joining, existing nodes from being maintained, or any metadata changes from being processed.

Technologies: [github.com/projectcapsule/capsule (Go)](https://junglewise.ai/threats/technologies/github-com-projectcapsule-capsule), [Project Capsule Capsule](https://junglewise.ai/threats/technologies/capsule). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Project Capsule](https://junglewise.ai/threats/vendors/project-capsule).

## Quick answers

**Is CVE-2026-65834 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-65834 being exploited in the wild.

**How severe is CVE-2026-65834?** Medium severity, with a CVSS score of 6.8, published 30 July 2026.

**Which products and versions are affected?** github.com/projectcapsule/capsule (Go) <= 0.13.7, SEMVER:introduced=0,fixed=0.13.8; Project Capsule Capsule < 0.13.8, <= 0.13.7.

**Is there a fix for CVE-2026-65834?** Yes. github.com/projectcapsule/capsule (Go): upgrade to 0.13.8 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-65834 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-65834?** Check whether you run github.com/projectcapsule/capsule (Go) or Project Capsule Capsule at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/projectcapsule/capsule (Go): upgrade to 0.13.8 or later

  ```sh
  go get github.com/projectcapsule/capsule@v0.13.8
  ```


## Technical details

The vulnerability is a denial-of-service (DoS) caused by a lack of input validation in the Capsule admission webhook. Specifically, the `ForbiddenLabels.Regex` and `ForbiddenAnnotations.Regex` fields in `CapsuleConfiguration` are not validated before being persisted to etcd. When a Node `CREATE`, `UPDATE`, or `PATCH` request occurs, the downstream consumer calls `regexp.MustCompile()` on these stored strings. Because `MustCompile` panics on invalid regex patterns, a malformed entry crashes the webhook process. This blocks all node-related operations cluster-wide, including autoscaling and maintenance. The issue was addressed in version 0.13.8 by adding a dedicated regex validator to the configuration webhook.

## Affected products

- Project Capsule Capsule <= 0.13.7

## Identifiers

- CVE-2026-65834
- GHSA-68cj-mvg9-rgm2
- GO-2026-6155

## Timeline

- 2026-07-08: disclosed
- 2026-07-31: advisory
- 2026-07-31: patched: Fixed in version 0.13.8

## References

- [https://api.github.com/users/PhucQuan](https://api.github.com/users/PhucQuan)
- [https://github.com/PhucQuan](https://github.com/PhucQuan)
- [https://api.github.com/users/PhucQuan/gists%7B/gist_id%7D](https://api.github.com/users/PhucQuan/gists%7B/gist_id%7D)
- [https://api.github.com/users/PhucQuan/repos](https://api.github.com/users/PhucQuan/repos)
- [https://avatars.githubusercontent.com/u/153093559?v=4](https://avatars.githubusercontent.com/u/153093559?v=4)
- [https://api.github.com/users/PhucQuan/events%7B/privacy%7D](https://api.github.com/users/PhucQuan/events%7B/privacy%7D)

## Related threats

- [Capsule hostnameRegexHandler parameter order bypass in webhook validation](https://junglewise.ai/threats/cve-2026-61795-capsule-hostnameregexhandler-parameter-order-bypass-in-webhook)
- [Capsule Tenant ForbiddenAnnotations.Regex validation bypass](https://junglewise.ai/threats/cve-2026-61794-capsule-tenant-forbiddenannotations-regex-validation-bypass)
- [Capsule forbidden namespace/service/node label and annotation enforcement bypass](https://junglewise.ai/threats/cve-2026-61672-capsule-forbidden-namespace-service-node-label-and-annotation)
- [Clastix Capsule incorrect authorization via typo in namespaces/finalize webhook](https://junglewise.ai/threats/cve-2026-55636-clastix-capsule-incorrect-authorization-via-typo-in-namespaces)
- [Project Capsule privilege escalation in TenantResource controller](https://junglewise.ai/threats/cve-2026-65835-project-capsule-privilege-escalation-in-tenantresource-controller)