PYSEC-2026-1975

Vulnerability from pysec - Published: 2026-07-07 14:34 - Updated: 2026-07-07 17:25
VLAI
Details

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.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impacted products
Name purl
tornado pkg:pypi/tornado
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "tornado",
        "purl": "pkg:pypi/tornado"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.4.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.2",
        "1.0",
        "1.1",
        "1.1.1",
        "1.2",
        "1.2.1",
        "2.0",
        "2.1",
        "2.1.1",
        "2.2",
        "2.2.1",
        "2.3",
        "2.4",
        "2.4.1",
        "3.0",
        "3.0.1",
        "3.0.2",
        "3.1",
        "3.1.1",
        "3.2",
        "3.2.1",
        "3.2.2",
        "4.0",
        "4.0.1",
        "4.0.2",
        "4.1",
        "4.1b2",
        "4.2",
        "4.2.1",
        "4.2b1",
        "4.3",
        "4.3b1",
        "4.3b2",
        "4.4",
        "4.4.1",
        "4.4.2",
        "4.4.3",
        "4.4b1",
        "4.5",
        "4.5.1",
        "4.5.2",
        "4.5.3",
        "4.5b1",
        "4.5b2",
        "5.0",
        "5.0.1",
        "5.0.2",
        "5.0a1",
        "5.0b1",
        "5.1",
        "5.1.1",
        "5.1b1",
        "6.0",
        "6.0.1",
        "6.0.2",
        "6.0.3",
        "6.0.4",
        "6.0a1",
        "6.0b1",
        "6.1",
        "6.1b1",
        "6.1b2",
        "6.2",
        "6.2b1",
        "6.2b2",
        "6.3",
        "6.3.1",
        "6.3.2",
        "6.3.3",
        "6.3b1",
        "6.4",
        "6.4.1",
        "6.4b1"
      ]
    }
  ],
  "aliases": [
    "CVE-2024-52804",
    "GHSA-8w49-h785-mj3c"
  ],
  "details": "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.\n\nSee also CVE-2024-7592 for a similar vulnerability in cpython.",
  "id": "PYSEC-2026-1975",
  "modified": "2026-07-07T17:25:42.423127Z",
  "published": "2026-07-07T14:34:45.585102Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/tornadoweb/tornado/security/advisories/GHSA-8w49-h785-mj3c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-52804"
    },
    {
      "type": "WEB",
      "url": "https://github.com/tornadoweb/tornado/commit/d5ba4a1695fbf7c6a3e54313262639b198291533"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/tornadoweb/tornado"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00000.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/tornado"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-8w49-h785-mj3c"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Tornado has an HTTP cookie parsing DoS vulnerability"
}



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