CVE-2026-65834
MEDIUMCVE-2026-65834 is a medium-severity (CVSS 6.8) Improper Input Validation vulnerability in github.com/projectcapsule/capsule. O3 Security confirms whether CVE-2026-65834 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Capsule: CapsuleConfiguration NodeMetadata regex fields lack webhook validation, allowing MustCompile panic on all Node admission requests
Blast Radius
github.com/projectcapsule/capsuleReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/projectcapsule/capsule | all versions | 0.13.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/projectcapsule/capsule. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/projectcapsule/capsule to 0.13.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-65834 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-65834 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-65834. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-65834 in your dependencies?
O3 detects CVE-2026-65834 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.