Description

@mobilenext/mobile-mcp alllows arbitrary file write via Path Traversal in mobile screen capture tools

Summary

The @mobilenext/mobile-mcp server contains a Path Traversal vulnerability in the mobile_save_screenshot and mobile_start_screen_recording tools. The saveTo and output parameters were passed directly to filesystem operations without validation, allowing an attacker to write files outside the intended workspace.

Details

File: src/server.ts (lines 584-592)

tool(
    "mobile_save_screenshot",
    "Save Screenshot",
    "Save a screenshot of the mobile device to a file",
    {
        device: z.string().describe("The device identifier..."),
        saveTo: z.string().describe("The path to save the screenshot to"),
    },...
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Root Cause

The saveTo parameter is passed directly to fs.writeFileSync() without any validation. The codebase has validation functions for other parameters (validatePackageName, validateLocale in src/utils.ts) but no path validation function exists.

Additional Affected Tool

File: src/server.ts (lines 597-620)

The mobile_start_screen_recording tool has the same vulnerability in its output parameter.

PoC

#!/usr/bin/env python3

import json
import os
import subprocess
import sys
import time
from datetime import datetime...
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Impact

A Prompt Injection attack from a malicious website or document could trick the AI into overwriting sensitive host files (e.g., ~/.bashrc, ~/.ssh/authorized_keys, or .config files) leading to a broken shell.

Mitigation

Aliases

References