Resource Exhaustion Affecting python3.13-tornado-debuginfo package, versions <0:6.4.2-1.amzn2023.0.2


Severity

Recommended
high

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.56% (44th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-AMZN2023-PYTHON313TORNADODEBUGINFO-15921316
  • published7 Apr 2026
  • disclosed12 Dec 2025

Introduced: 12 Dec 2025

CVE-2025-67725  (opens in a new tab)
CWE-400  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 python3.13-tornado-debuginfo to version 0:6.4.2-1.amzn2023.0.2 or higher.
This issue was patched in ALAS2023-2026-1528.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3.13-tornado-debuginfo package and not the python3.13-tornado-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

Tornado is a Python web framework and asynchronous networking library. In versions 6.5.2 and below, a single maliciously crafted HTTP request can block the server's event loop for an extended period, caused by the HTTPHeaders.add method. The function accumulates values using string concatenation when the same header name is repeated, causing a Denial of Service (DoS). Due to Python string immutability, each concatenation copies the entire string, resulting in O(n²) time complexity. The severity can vary from high if max_header_size has been increased from its default, to low if it has its default value of 64KB. This issue is fixed in version 6.5.3.

CVSS Base Scores

version 3.1