Capsule: CapsuleConfiguration NodeMetadata regex fields lack webhook validation, allowing MustCompile panic on all Node admission requests

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.8 · CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H

EPSS

• CVE-2026-65834: 0.32% estimated exploitation activity in the next 30 days; percentile 25.31 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary CapsuleConfiguration.Spec.NodeMetadata.ForbiddenLabels.Regex and ForbiddenAnnotations.Regex are never validated by any admission webhook. A Cluster Admin can persist a malformed regex to etcd without being blocked. Once stored, every Node CREATE, UPDATE, or PATCH request triggers regexp.MustCompile() in pkg/api/forbiddenlist.go:36, which panics and crashes the node admission webhook — causing a cluster-wide Denial of Service for all Node operations. Root cause internal/webhook/tenant/validation/ contains dedicated regex validators for every Tenant regex field (hostname, storageclass, ingressclass, containerregistry, etc.). internal/webhook/cfg/ contains no regex validator at all — only owners.go, serviceaccount.go, and warnings.go. The downstream consumer internal/webhook/node/usermetadata.go calls: Which routes to pkg/api/forbiddenlist.go:36: Unlike regexp.Compile, regexp.MustCompile panics instead of returning an error. Since no webhook validates the CapsuleConfiguration…

Published by the source

31 Jul 2026, 16:53 UTC

Last modified by the source

18 Aug 2026, 15:00 UTC

Source last checked

26 Oct 2026, 15:28 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-68cj-mvg9-rgm2

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6155

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-68cj-mvg9-rgm2

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# Patch Next advisory brief: CVE-2026-65834

Advisory: Capsule: CapsuleConfiguration NodeMetadata regex fields lack webhook validation, allowing MustCompile panic on all Node admission requests
IDs: CVE-2026-65834, GHSA-68cj-mvg9-rgm2
Record: https://patchnext.com/advisories/cve-2026-65834 (revision 3, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/projectcapsule/capsule 0.13.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/projectcapsule/capsule: affected <= 0.13.7; fixed in 0.13.8

## Suggested inspection (read-only)
- Go github.com/projectcapsule/capsule: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/projectcapsule/capsule.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-68cj-mvg9-rgm2 (OSV record GHSA-68cj-mvg9-rgm2 lists affected ranges: Go github.com/projectcapsule/capsule >=0 <0.13.8 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6155 (OSV record GO-2026-6155 lists affected ranges: Go github.com/projectcapsule/capsule >=0 <0.13.8 (fixed))
- Verified: https://github.com/advisories/GHSA-68cj-mvg9-rgm2 (GitHub-reviewed advisory GHSA-68cj-mvg9-rgm2 lists affected ranges: Go github.com/projectcapsule/capsule >=0 <=0.13.7)

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