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Quart 0.23.0 leaks raw request body (incl. plaintext passwords) to stdout via stray debug print in Body.__await__

Low
pgjones published GHSA-v853-p72q-4cfw Aug 29, 2026

Package

pip quart (pip)

Affected versions

0.23.0

Patched versions

None

Description

Description — the form gives you 4 pre-built headers (Summary/Details/PoC/Impact). Replace the placeholder italics under each with this:

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).

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N

CVE ID

No known CVE

Weaknesses

Insertion of Sensitive Information into Log File

The product writes sensitive information to a log file. Learn more on MITRE.