MCP Watch is a comprehensive security scanner for Model Context Protocol (MCP) servers. In 0.1.2 and earlier, the MCPScanner class contains a critical Command Injection vulnerability in the cloneRepo method. The application passes the user-supplied githubUrl argument directly to a system shell via execSync without sanitization. This allows an attacker to execute arbitrary commands on the host machine by appending shell metacharacters to the URL.

Affected: npm: mcp-watch

### Summary The `MCPScanner ` class contains a critical Command Injection vulnerability in the `cloneRepo `method. The application passes the user-supplied githubUrl argument directly to a system shell via execSync without sanitization. This allows an attacker to execute arbitrary commands on the host machine by appending shell metacharacters to the URL.

### Details The vulnerability exists in the src/scanner/MCPScanner.ts file within the cloneRepo method.

[https://github.com/kapilduraphe/mcp-watch/blob/0fca7228bd313ae5aa938d61311377e88ce6e682/src/scanner/McpScanner.ts#L181](https://github.com/kapilduraphe/mcp-watch/blob/0fca7228bd313ae5aa938d61311377e88ce6e682/src/scanner/McpScanner.ts#L181)

The code uses child_process.execSync to execute a git clone command:

Because execSync spawns a shell (defaulting to `/bin/sh` on Unix or` cmd.exe` on Windows), any shell metacharacters present in the url argument will be interpreted by the shell. The application does not validate that the url is a valid Git URL, nor does it sanitize input for shell metacharacters.

### PoC Install the package or clone the repository.

Run the scanner using the CLI (or invoke scanRepository programmatically).

Provide a malicious URL containing a command separator (e.g., ;, &, or |) and a system command. payload : `npm run scan:github "https://github.com/kapilduraphe/mcp-watch & calc.exe"`

<img width="1918" height="1046" alt="image" src="https://github.com/user-attachments/assets/021c1dfa-3f87-483c-…