---
cve: "CVE-2025-67726"
severity: "HIGH"
cvss: 7.5
epss: "54%"
vendor: "tornadoweb"
kev: false
exploited: false
published: "2025-12-12 07:15:44"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-11T03:46:17+02:00"
---

# CVE-2025-67726

> 7.5 HIGH · 🧪 PoC

## Beschreibung

Tornado is a Python web framework and asynchronous networking library. Versions 6.5.2 and below use an inefficient algorithm when parsing parameters for HTTP header values, potentially causing a DoS. The _parseparam function in httputil.py is used to parse specific HTTP header values, such as those in multipart/form-data and repeatedly calls string.count() within a nested loop while processing quoted semicolons. 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. This issue is fixed in version 6.5.3.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- 38014ddb51520ff7762c1d55535925dba2cdbe31 (Commit)
- 771472cfdaeebc0d89a9cc46e249f8891a6b29cd (Commit)

## Referenzen

- <https://github.com/tornadoweb/tornado/security/advisories/GHSA-jhmp-mqwm-3gq8>
- <https://github.com/tornadoweb/tornado/commit/771472cfdaeebc0d89a9cc46e249f8891a6b29cd>
- <https://github.com/tornadoweb/tornado/releases/tag/v6.5.3>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-67726) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_