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

Summary

## Summary 9router exposes two unauthenticated API endpoints that, when chained together, allow any network-adjacent attacker to execute arbitrary OS commands as the user running the 9router process — with **zero prerequisites** and **no credentials required**. The vulnerability exists because the Next.js middleware that enforces authentication (`src/proxy.js`) only guards 8 explicitly listed routes. The attack…

Product

npm: 9router

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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