CVE-2026-46339 json
9Router: Unauthenticated Remote Code Execution via unprotected MCP custom plugin routes
published 5mo ago modified 16d ago also GHSA-fhh6-4qxv-rpqj , EUVD-2026-44808
- cvss
- 10.0
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 2.8%
- EPSS 2.8% chance of exploitation in 30 days, percentile 86%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
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.
Patch / fix
Is CVE-2026-46339 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- total
- Assessed
- 3mo ago
Exploit prediction
2.76% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- Nuclei template 9Router <= 0.4.36 - Unauthenticated RCE nuclei detection template
- github.com https://github.com/decolua/9router/security/advisories/GHSA-fhh6-4qxv-rpqj referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
| GitHub | 3.1 | 10.0 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | 9router | >=0.4.30, <0.4.37 |
0.4.37 |
Affected products
- decolua 9router
Classification
References
Sources
- CVE List CVE-2026-46339
- GitHub Advisory GHSA-fhh6-4qxv-rpqj
- NVD CVE-2026-46339
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