CVE-2024-52804Network attack vector

Request-processing denial of service via quadratic cookie unquoting

Published Nov 22, 2024 · Updated Nov 3, 2025

Denial of service in Tornado before 6.4.2 allows remote attackers to block request processing via crafted HTTP Cookie headers. The _unquote_cookie function repeatedly searches the remaining quoted value for escape patterns, making parsing quadratic instead of linear. An unauthenticated request to a Tornado HTTP server is sufficient, and CPU work on its event-loop thread delays every other request handled there.

CVSS severity7.5
High
EPSS probability1.04%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Tornado before 6.4.2 allows remote attackers to block request processing via crafted HTTP Cookie headers. The _unquote_cookie function repeatedly searches the remaining quoted value for escape patterns, making parsing quadratic instead of linear. An unauthenticated request to a Tornado HTTP server is sufficient, and CPU work on its event-loop thread delays every other request handled there.

The record

CVE
CVE-2024-52804
Published
Nov 22, 2024
Updated
Nov 3, 2025
Vendor
tornadoweb
Product
Tornado
Classifications
CWE-400, CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 22, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <6.4.2
  2. Affected versionversion=< 6.4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

tornadoweb · Tornadoversion=0 <6.4.2; version=< 6.4.2

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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