Vulnerability · Published Jul 15, 2026 · Assigned by GitHub_M

CVE-2026-623129Router: Authenticated RCE via Unvalidated MCP Plugin Arguments

High 8.8

In plain English

A high-severity OS command injection in 9router from decolua. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.9% (higher than 61% of all known vulnerabilities).

Severity (CVSS 3.1)8.8High

Exploit odds (30 days)0.9%top 39.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

9Router is an AI router & token saver. Prior to 0.5.2, 9Router allows a remote authenticated attacker to achieve arbitrary code execution on the host operating system by combining a Host header bypass of localhost-only routes with unvalidated MCP plugin args passed to child_process.spawn(), allowing malicious custom plugins to execute commands through /api/mcp//sse. This issue is fixed in version 0.5.2.

Affected products (as reported)

Vendor	Product	Versions
decolua	9router	< 0.5.2

Weakness: CWE-78 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

https://github.com/decolua/9router/security/advisories/GHSA-63p9-g54h-prrp x_refsource_CONFIRM
https://github.com/decolua/9router/commit/da667836cc7584bea0edd893de1d590c9ea279dc x_refsource_MISC
https://github.com/decolua/9router/releases/tag/v0.5.2 x_refsource_MISC