CVE-2026-40304
MEDIUMCVE-2026-40304 is a medium-severity (CVSS 5.3) vulnerability in github.com/openziti/zrok. O3 Security confirms whether CVE-2026-40304 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
zrok's broken ownership check in DELETE /api/v2/unaccess allows non-admin to delete global frontend records
Real-World Exposure
github.com/openziti/zrok🐹github.com/openziti/zrok/v2Real-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
zrok is software for sharing web services, files, and network resources. Prior to version 2.0.1, the unaccess handler (controller/unaccess.go) contains a logical error in its ownership guard: when a frontend record has environment_id = NULL (the marker for admin-created global frontends), the condition short-circuits to false and allows the deletion to proceed without any ownership verification. A non-admin user who knows a global frontend token can call DELETE /api/v2/unaccess with any of their own environment IDs and permanently delete the global frontend, taking down all public shares routed through it. Version 2.0.1 patches the issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/openziti/zrok | all versions | No fix |
| 🐹Go | github.com/openziti/zrok/v2 | all versions | 2.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openziti/zrok. 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
No patched version of github.com/openziti/zrok has shipped for CVE-2026-40304 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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-2026-40304 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-2026-40304. 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-2026-40304 in your dependencies?
O3 detects CVE-2026-40304 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.