---
id: CVE-2024-52804
aliases:
  - GHSA-8w49-h785-mj3c
  - PYSEC-2026-1975
title: Tornado has an HTTP cookie parsing DoS vulnerability
summary: Tornado has an HTTP cookie parsing DoS vulnerability
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: tornado
product: tornado
ecosystem: pip
affected:
  - tornado < 6.4.2
patched:
  - tornado 6.4.2
published: '2024-11-22'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:20.413166306Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-8w49-h785-mj3c'
references:
  - url: >-
      https://github.com/tornadoweb/tornado/security/advisories/GHSA-8w49-h785-mj3c
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2024-52804'
  - url: >-
      https://github.com/tornadoweb/tornado/commit/d5ba4a1695fbf7c6a3e54313262639b198291533
  - url: 'https://github.com/tornadoweb/tornado'
  - url: 'https://lists.debian.org/debian-lts-announce/2025/01/msg00000.html'
tags:
  - osv
  - pip
epss: 0.01044
epssPercentile: 0.62686
ingestedAt: '2026-07-08T18:25:47.559Z'
---

## Overview

The algorithm used for parsing HTTP cookies in Tornado versions prior to 6.4.2 sometimes has quadratic complexity, leading to excessive CPU consumption when parsing maliciously-crafted cookie headers. This parsing occurs in the event loop thread and may block the processing of other requests.

See also CVE-2024-7592 for a similar vulnerability in cpython.

## Affected packages

- `tornado < 6.4.2`

## Remediation

Upgrade to a patched release:

- `tornado 6.4.2`