Which products and versions are affected by CVE-2026-46339?

Affected: 9router (npm) versions >= 0.4.30, >= 0.4.30,. The full list is in the CVE brief.

Is CVE-2026-46339 being exploited in the wild?

It is not listed in any known-exploited vulnerabilities catalog.

Is CVE-2026-46339 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2026-46339?

Public exploit code is available.

Is there a fix for CVE-2026-46339?

Fixed versions are available, including 9router 0.4.37.

How urgently should CVE-2026-46339 be patched?

Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.

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Vulnerability Intelligence

CVE-2026-46339

CriticalPublic exploit

9router: Unauthenticated Remote Code Execution via unprotected MCP custom plugin routes

Published May 19, 2026 · Updated Aug 12, 2026 · Also known as EUVD-2026-44808, GHSA-fhh6-4qxv-rpqj

Key Facts

Patch immediately

CVE-2026-46339 is a critical-severity vulnerability (CVSS 10.0 v3.1) affecting 9router (npm).
It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
EPSS estimates a 3.4% probability of exploitation in the next 30 days.
Fixed versions are available, including 9router 0.4.37.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.

CVSS v3.1

10.0

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

EPSS (30-day exploit likelihood)

3.4%

Higher than 88.5% of all scored CVEs

Exploited in the wild

No known

Not in a known-exploited catalog

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2026-46339 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

Description

9Router is an AI router & token saver. From 0.4.30 until 0.4.37, 9Router's src/proxy.js middleware did not protect /api/cli-tools/* and /api/mcp/*, allowing unauthenticated registration of customPlugins through src/app/api/cli-tools/cowork-settings/route.js and command execution through the MCP bridge. This vulnerability is fixed in 0.4.37.

Affected Products

2 affected entries in total

Product	Affected versions	Fixed in
9routernpm	>= 0.4.30, >= 0.4.30,	0.4.37

Patched Releases

9router

0.4.37

Timeline

Publicly disclosed
May 19, 2026
Last updated
Aug 12, 2026

Weakness Type

CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-306 Missing Authentication for Critical Function

References

1 more references in the full CVE brief

FAQ

Common Questions.

9Router is an AI router & token saver.
Affected: 9router (npm) versions >= 0.4.30, >= 0.4.30,. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including 9router 0.4.37.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.

Is CVE-2026-46339 Running On Your Attack Surface?

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