DEBIAN-CVE-2025-67726

Advisory lineage Upstream: 1 Downstream: 0
Upstream
CVE-2025-67726
Published: 12 Dec 2025, 07:15
Last modified:28 Apr 2026, 20:30

Vulnerability Summary

Overall Risk (default)
medium
30/100
CVSS Score
7.5 HIGH
3.1 (osv_debian)
EPSS Score
No data
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

12 Dec 2025, 07:15
Published
Vulnerability first disclosed
28 Apr 2026, 20:30
Last Modified
Vulnerability information updated

Description

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 Metrics

  • v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Systems

  • debian•python-tornado

    all | all | < 6.1.0-1+deb11u3 | < 6.2.0-3+deb12u4 | < 6.4.2-3+deb13u2 | < 6.5.4-0.1

References (1)