Quart leaks raw request body (incl. plaintext passwords) to stdout via stray debug print in Body.__await__

Summary

Quart 0.23.0 contains a stray debug statement (print(data)) inside Body.__await__ in quart/wrappers/request.py. Any request whose body is awaited — await request.form, await request.get_data(), WTForms validate_on_submit(), etc. — has its raw, unparsed body printed to stdout, including plaintext form fields such as passwords and CSRF tokens. Confirmed present in 0.23.0, confirmed absent in 0.22.0.

Details

In src/quart/wrappers/request.py, Body.__await__ accumulates the request body into a bytearray:

​python data = bytearray() while not self._queue.empty(): data.extend(self._queue.get_nowait()) print(data) # <-- not present in 0.22.0 if ( self._max_content_length is not None and len(data) > self._max_content_length ): raise RequestEntityTooLarge() ​

This fires for every request that awaits its body — the overwhelming majority of POST/PUT routes in a typical Quart app (form submissions, JSON APIs via request.get_json(), file uploads, etc.).

PoC

1. pip install quart==0.23.0 (requires Python 3.13+)
2. Minimal route: ​python @app.route("/login", methods=["POST"]) async def login(): form_data = await request.form ... ​
3. Submit a POST with form data, e.g. a login form with staff_id/password fields.
4. Observe stdout: the full raw body is printed as bytearray(b'csrf_token=...&staff_id=...&password=...').

Confirmed via source diff against 0.22.0's request.py, where this line does not exist.

Impact

Any app that captures stdout in logs (terminal redirect, systemd/journald, Docker logs, cloud log aggregation, etc.) will have every submitted form body — including login credentials — written to logs in plaintext. This affects any Quart 0.23.0 app handling authentication or any sensitive form data, and is trivially triggerable by any user simply submitting a form (no attacker action required beyond normal use).