Patched code sample

# This code is a simplified representation of the fix for CVE-2024-27167,
# based on the changes made in the Gradio source code (e.g., in gradio/routes.py).
# The vulnerability was that a "mocked" OAuth flow, intended for local development,
# was enabled by default on self-hosted applications. This flow exposed the
# server's Hugging Face token to any remote user.

# The fix introduces a new parameter, `enable_mocked_oauth`, which defaults
# to False. This ensures the vulnerable code path is not accessible unless
# a developer explicitly opts in for local testing purposes.

from typing import Optional
from fastapi import Request, Response
from huggingface_hub import utils as hf_hub_utils


# A simplified representation of the Gradio App class structure
class App:
    def __init__(
        self,
        space_id: Optional[str] = None,
        # THE FIX: A new parameter `enable_mocked_oauth` is introduced, defaulting to `False`.
        # This disables the vulnerable mocked OAuth flow by default for self-hosted apps.
        enable_mocked_oauth: bool = False,
        # ... other parameters
    ):
        self.space_id = space_id
        self.enable_mocked_oauth = enable_mocked_oauth
        # ... other initializations

        # In the original code, the logic to add routes is here.
        # The fix ensures these routes are only added if running on Hugging Face Spaces
        # (self.space_id is not None) OR if the developer explicitly enables the mock flow.
        if self.enable_mocked_oauth or self.space_id:
            # In a real app, this would add the route:
            # self.add_api_route("/login/huggingface", self.login_huggingface, methods=["GET"])
            pass

    async def login_huggingface(self, request: Request) -> Response:
        """
        This method handles the Hugging Face login flow.
        The fix is demonstrated in the `if not self.space_id:` block.
        """
        # If running on a Hugging Face Space, the real (secure) OAuth flow is used.
        # This part of the logic was not the source of the vulnerability.
        if self.space_id:
            # ... code for the real OAuth flow on Hugging Face Spaces ...
            return Response("Redirecting to real Hugging Face OAuth...", status_code=302)

        # This block handles the "mocked" login for self-hosted apps.
        # This is where the vulnerability existed and was fixed.
        if not self.space_id:
            # THE FIX: This condition now checks the `enable_mocked_oauth` flag.
            # If it's False (the default), it returns a 404 Not Found error,
            # preventing access to the vulnerable logic.
            if not self.enable_mocked_oauth:
                return Response(
                    content="Mocked OAuth is disabled. Set `enable_mocked_oauth=True` in `gr.Blocks()` to enable.",
                    status_code=404,
                )

            # This vulnerable code block is now only reachable if a developer
            # has explicitly set `enable_mocked_oauth=True` for local testing.
            #
            # Previously, this block would execute unconditionally for any
            # self-hosted Gradio app using an OAuth component.
            try:
                # Step that caused the vulnerability: getting the SERVER's token.
                token = hf_hub_utils.get_token()
                if token is None:
                    return Response("Server not logged in to Hugging Face Hub", status_code=500)
            except hf_hub_utils.HfHubLoginError:
                return Response("Server not logged in to Hugging Face Hub", status_code=500)

            # Step that caused the vulnerability: setting the server's token
            # in the VISITOR's session cookie.
            response = Response(status_code=302, headers={"Location": "/"})
            response.set_cookie(key="access-token-unsecure", value=token)
            return response

        return Response("This code path should not be reached.", status_code=500)