CVE-2024-1561: Gradio: path traversal enables arbitrary file read

An issue was discovered in gradio-app/gradio, where the `/component_server` endpoint improperly allows the invocation of any method on a `Component` class with attacker-controlled arguments. Specifically, by exploiting the `move_resource_to_block_cache()` method of the `Block` class, an attacker can copy any file on the filesystem to a temporary directory and subsequently retrieve it. This vulnerability enables unauthorized local file read access, posing a significant risk especially when the application is exposed to the internet via `launch(share=True)`, thereby allowing remote attackers to read files on the host machine. Furthermore, gradio apps hosted on `huggingface.co` are also affected, potentially leading to the exposure of sensitive information such as API keys and credentials stored in environment variables.

Attacker scans Shodan/Censys for exposed Gradio apps or follows a share=True link shared in a public GitHub repo or Slack. They POST to /component_server with method move_resource_to_block_cache and a path argument pointing to /proc/self/environ or ~/.env. Gradio copies the file to its temp cache directory and returns it on the next request. The attacker extracts HF_TOKEN, OPENAI_API_KEY, and AWS credentials in under 60 seconds. On HuggingFace Spaces, this translates to full HF account takeover — the attacker can download all private models, push poisoned model weights, or pivot to other services using the extracted credentials. No specialized knowledge required; a simple curl command suffices.