zrok: Broken ownership check in DELETE /api/v2/unaccess allows non-admin to delete global frontend records

Exploitation

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

CVSS

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

EPSS

• CVE-2026-40304: 0.29% estimated exploitation activity in the next 30 days; percentile 21.18 (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 The unaccess handler (controller/unaccess.go) contains a logical error in its ownership guard: when a frontend record has environmentid = 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. Attack Vector: Network — the endpoint is a standard HTTP API call. Attack Complexity: High — successful exploitation requires prior knowledge of a global frontend token. These tokens are not returned to non-admin users by any standard API endpoint; obtaining one requires an out-of-band step (e.g., leaked server logs, admin documentation for a self-hosted instance, or social engineering). Privileges Required: Low — a valid user account with at least one registered…

Published by the source

16 Apr 2026, 21:09 UTC

Last modified by the source

24 Apr 2026, 20:49 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3jpj-v3xr-5h6g

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# Patch Next advisory brief: CVE-2026-40304

Advisory: zrok: Broken ownership check in DELETE /api/v2/unaccess allows non-admin to delete global frontend records
IDs: CVE-2026-40304, GHSA-3jpj-v3xr-5h6g
Record: https://patchnext.com/advisories/cve-2026-40304 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/openziti/zrok/v2 2.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/openziti/zrok: affected <= 1.1.11
- Go github.com/openziti/zrok/v2: affected < 2.0.1; fixed in 2.0.1

## Suggested inspection (read-only)
- Go github.com/openziti/zrok: check the installed version with your package manager.
- Go github.com/openziti/zrok/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/openziti/zrok, github.com/openziti/zrok/v2.
- 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://github.com/advisories/GHSA-3jpj-v3xr-5h6g (GitHub-reviewed advisory GHSA-3jpj-v3xr-5h6g lists affected ranges: Go github.com/openziti/zrok >=0 =0 <2.0.1)

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