GHSA-jhmp-mqwm-3gq8

Suggest an improvement
Source
https://github.com/advisories/GHSA-jhmp-mqwm-3gq8
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-jhmp-mqwm-3gq8/GHSA-jhmp-mqwm-3gq8.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-jhmp-mqwm-3gq8
Aliases
Downstream
ECHO (1)
MINI (2)
Published
2026-07-20T18:57:54Z
Modified
2026-07-20T19:15:27Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
Tornado: Quadratic DoS via Crafted Multipart Parameters
Details

Summary

The _parseparam function in Tornado's httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data. This function uses an inefficient algorithm that repeatedly calls string.count() within a nested loop while processing quoted semicolons (e.g., param=";").

As a result, if an attacker sends a request with a large number of maliciously crafted parameters in a Content-Disposition header, the server's CPU usage increases quadratically (O(n²)) during parsing. Due to Tornado's single event loop architecture, a single malicious request can cause the entire server to become unresponsive for an extended period, leading to a Denial of Service (DoS).

Severity: High

Database specific 
{
    "cwe_ids":  [
        "CWE-400"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-07-20T18:57:54Z",
    "nvd_published_at":  "2025-12-12T07:15:44Z",
    "severity":  "HIGH"
}
References

Affected packages

PyPI / tornado

Package

Name
tornado
View open source insights on deps.dev
Purl
pkg:pypi/tornado

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
6.5.3

Affected versions

0.*
0.2
1.*
1.0
1.1
1.1.1
1.2
1.2.1
2.*
2.0
2.1
2.1.1
2.2
2.2.1
2.3
2.4
2.4.1
3.*
3.0
3.0.1
3.0.2
3.1
3.1.1
3.2
3.2.1
3.2.2
4.*
4.0
4.0.1
4.0.2
4.1b2
4.1
4.2b1
4.2
4.2.1
4.3b1
4.3b2
4.3
4.4b1
4.4
4.4.1
4.4.2
4.4.3
4.5b1
4.5b2
4.5
4.5.1
4.5.2
4.5.3
5.*
5.0a1
5.0b1
5.0
5.0.1
5.0.2
5.1b1
5.1
5.1.1
6.*
6.0a1
6.0b1
6.0
6.0.1
6.0.2
6.0.3
6.0.4
6.1b1
6.1b2
6.1
6.2b1
6.2b2
6.2
6.3b1
6.3
6.3.1
6.3.2
6.3.3
6.4b1
6.4
6.4.1
6.4.2
6.5b1
6.5
6.5.1
6.5.2

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-jhmp-mqwm-3gq8/GHSA-jhmp-mqwm-3gq8.json"