medium

MCP server launched through a shell

The command is bash, sh, cmd, powershell or similar, with the real server started from a shell string.

Why it matters

A shell makes it easy for arguments or environment values to run extra commands, and hides what actually executes.

Call the server's executable directly with an argument list.

{
  "mcpServers": {
    "db": {
      "command": "bash",
      "args": [
        "-c",
        "cd ~/db && node server.js"
      ]
    }
  }
}

{
  "mcpServers": {
    "db": {
      "command": "node",
      "args": [
        "/home/alex/db/server.js"
      ]
    }
  }
}

Illustrative configs. The checker flags the “before” version with this finding and not the “after” version.