Vulnerable code sample

import subprocess
from flask import Flask, request, jsonify
from functools import wraps

# This is a simplified representation of the vulnerable application structure.
# WARNING: This code is intentionally vulnerable for demonstration purposes.
# Do NOT use this in a production environment.

app = Flask(__name__)

# The allowlist of binaries as described in the CVE.
ALLOWED_COMMANDS = ['python3', 'node', 'deno', 'bun']

# A mock authentication decorator. The CVE states only 'requireAuth' is needed,
# meaning any authenticated user can exploit this, not just an owner/admin.
def require_auth(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        # In a real app, this would validate a JWT or session cookie.
        # For this example, we just check for a header's existence.
        if 'Authorization' not in request.headers:
            return jsonify({"error": "Authentication required"}), 401
        return f(*args, **kwargs)
    return decorated_function

# The vulnerable MCP server creation endpoint.
@app.route('/api/mcp/create_server', methods=['POST'])
@require_auth
def create_mcp_server():
    """
    Vulnerable endpoint that allows arbitrary code execution.
    - It validates the 'command' field against an allowlist.
    - It FAILS to validate the 'args' field, passing them directly to subprocess.
    """
    try:
        data = request.get_json()
        if not data or 'command' not in data or not isinstance(data.get('args'), list):
            return jsonify({"error": "Invalid request body. 'command' and 'args' (list) are required."}), 400

        command = data.get('command')
        args = data.get('args')

        # Part 1: The command is validated against the allowlist. This provides a false sense of security.
        if command not in ALLOWED_COMMANDS:
            return jsonify({"error": f"Command '{command}' is not in the allowlist."}), 403

        # Part 2: THE VULNERABILITY
        # The 'args' array is passed directly to the child process without any sanitization or validation.
        # An attacker can provide an inline code execution flag (e.g., -c for python3, -e for node)
        # followed by malicious code.
        
        # Malicious payload example:
        # {
        #   "command": "python3",
        #   "args": ["-c", "import os; os.system('touch /tmp/pwned_by_cve')"]
        # }
        
        full_command_list = [command] + args
        
        # The command and its unsanitized arguments are executed.
        process = subprocess.Popen(full_command_list, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

        return jsonify({
            "status": "success",
            "message": f"Server process for '{command}' started.",
            "pid": process.pid
        }), 201

    except Exception as e:
        return jsonify({"error": "An internal error occurred", "details": str(e)}), 500

if __name__ == '__main__':
    # Binds on all interfaces ('::' or '0.0.0.0'), making it network-accessible as described.
    app.run(host='0.0.0.0', port=8080)