/Vulnerability Library

9Router <= 0.4.36 - Unauthenticated RCE

CVE-2026-46339
Verified

Description

9Router <= 0.4.36 middleware only guards 8 explicitly listed routes, leaving /api/cli-tools/* and /api/mcp/* entirely unauthenticated. An attacker can POST to /api/cli-tools/cowork-settings to register a custom MCP plugin with attacker-controlled command and args stored verbatim into globalThis, then GET /api/mcp/{name}/sse to trigger spawn() with the stored command resulting in unauthenticated remote code execution.

Severity

Critical

CVSS Score

10

Exploit Probability

3%

Affected Product

9router

Published Date

July 14, 2026

Template Author

0x_akoko

CVE-2026-46339.yaml
10.0Score

CVSS Metrics

CVSS Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVE ID:
cve-2026-46339
CWE ID:
cwe-78

References

https://github.com/decolua/9router/security/advisories/GHSA-fhh6-4qxv-rpqjhttps://nvd.nist.gov/vuln/detail/CVE-2026-46339

Remediation Steps

Upgrade to 9Router 0.4.37 or later.