Patched code sample

import click

# This code represents the fix for the vulnerability described.
# The original vulnerable code defaulted the 'host' parameter to '0.0.0.0',
# which binds the server to all network interfaces, making it accessible
# to any network-adjacent caller.
#
# The fix, shown below, is to change the default value for 'host' to
# '127.0.0.1'. This ensures that by default, the server only binds to the
# localhost interface and is not exposed to the network, mitigating the
# "confused-deputy" vulnerability. The user must now explicitly set
# --host 0.0.0.0 to achieve the previous, less secure behavior.

@click.command()
@click.option(
    "--host",
    # This default value is the fix. It was previously "0.0.0.0".
    default="127.0.0.1",
    show_default=True,
    help="The host on which to run the server.",
)
@click.option(
    "--port",
    default=8080,
    show_default=True,
    help="The port on which to run the server.",
)
def serve(host, port):
    """
    A simplified representation of the mcp-pinot server startup command.
    The key change is the default value for the '--host' option.
    """
    print(f"Starting server on http://{host}:{port}...")

    if host == "127.0.0.1":
        print("FIX APPLIED: Server is correctly bound to localhost by default.")
    elif host == "0.0.0.0":
        print("WARNING: Server is bound to all interfaces and is network-accessible.")

    # In the actual application, this function would proceed to start
    # a web server (e.g., using wsgiref.simple_server) with the provided
    # host and port.
    #
    # from wsgiref.simple_server import make_server, demo_app
    # with make_server(host, port, demo_app) as httpd:
    #     httpd.serve_forever()

if __name__ == '__main__':
    # Running the script without arguments uses the new, secure default.
    # > python your_script_name.py
    # Output:
    # Starting server on http://127.0.0.1:8080...
    # FIX APPLIED: Server is correctly bound to localhost by default.
    serve()