What is CVE-2026-40304?

CVE-2026-40304 is a medium-severity vulnerability in Netfoundry Zrok, classified under Improper Access Control. CVSS score: 5.3/10. Published 2026-04-17.

How severe is CVE-2026-40304?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Auth bypass in Netfoundry Zrok

CVE-2026-40304

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.

Published 2026-04-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.004 (27.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 27th percentile — 27.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001

Affected products

Netfoundry Zrok
Openziti Zrok — versions < 2.0.1

Weakness classification (CWE)

References

github.com/openziti/zrok/security/advisories/GHSA-3jpj-v3xr-5h6g (Vendor Advisory)
github.com/openziti/zrok/releases/tag/v2.0.1 (Release Notes)

Frequently asked questions

What is CVE-2026-40304?: CVE-2026-40304 is a medium-severity vulnerability in Netfoundry Zrok, classified under Improper Access Control. CVSS score: 5.3/10. Published 2026-04-17.
How severe is CVE-2026-40304?: Medium severity. CVSS v3 base score is 5.3 out of 10.