GHSA-fhh6-4qxv-rpqj: 9router: Unauthenticated Remote Code Execution via unprotected MCP custom plugin routes

9router, a tool for managing AI plugins, has a critical vulnerability where two unprotected API endpoints can be chained together to run arbitrary OS commands. The problem occurs because the authentication middleware (a security check) only protects 8 specific routes, while 40+ routes under `/api/cli-tools/*` and `/api/mcp/*` have no protection, allowing attackers with network access to register malicious commands and then trigger them without any credentials.