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

Moderate severity GitHub Reviewed Published Apr 16, 2026 in openziti/zrok • Updated Apr 24, 2026

Package

gomod github.com/openziti/zrok (Go)

Affected versions

<= 1.1.11

Patched versions

None
gomod github.com/openziti/zrok/v2 (Go)
< 2.0.1
2.0.1

Description

Summary
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.

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 environment is required; no admin privileges needed.

User Interaction: None.

Scope: Unchanged — the impact stays within the same server instance.

Confidentiality Impact: None — no data is disclosed.

Integrity Impact: None — no data is improperly modified; the record is deleted (not corrupted).

Availability Impact: High — deleting a global frontend disrupts every public share routed through it on the instance, constituting a platform-wide availability impact.

Affected Component
controller/unaccess.go — unaccessHandler.Handle (line 56)

References

@mikegorman-nf mikegorman-nf published to openziti/zrok Apr 16, 2026
Published to the GitHub Advisory Database Apr 16, 2026
Reviewed Apr 16, 2026
Published by the National Vulnerability Database Apr 17, 2026
Last updated Apr 24, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(2nd percentile)

Weaknesses

Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Learn more on MITRE.

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. Learn more on MITRE.

CVE ID

CVE-2026-40304

GHSA ID

GHSA-3jpj-v3xr-5h6g

Source code

Credits

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