Tornado: Unbounded query-string argument count allows event-loop-stalling DoS — GHSA-3HV7-MJH2-FV65

Summary

## Summary `HTTPServerRequest.__init__` in `tornado/httputil.py` parses the URL query string via `parse_qs_bytes()` with no field-count limit — while the sibling POST-body parsing path (`parse_body_arguments`) received a `max_num_fields=1000` cap added earlier in this exact same release (v6.5.8, commit `8d6363ed`), explicitly to bound parsing cost for the identical underlying primitive. This leaves the query-string…

Timeline

Published by source

2026-09-30

Risk context

• Reported severity or threat level: medium.
• Reported CVSS score: 5.3 out of 10.
• Review exposure for the affected product or family: pip: tornado.

Product

pip: tornado

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source

Evidence and provenance

Canonical advisory ID

GHSA-3HV7-MJH2-FV65

Source

GitHub

Vendor

GitHub

Published by source

2026-09-30

Last source activity

2026-09-30

Curated by

hlukh.ch

Related advisories and connections

These advisories are connected by shared CVE, product, vendor, source, or time signals.