Fastapi

A Pyodide client serializes requests with pickle obfuscated by a hardcoded XOR key, letting the server pickle.loads attacker data for unauthenticated root RCE, then hooking the live handler to capture the adminbot’s plaintext login password.

A FastAPI app builds Pydantic models from user-supplied field definitions, where each string value is eval()ed as a forward-reference annotation, yielding arbitrary code execution and flag exfiltration via the JSON schema.