Critical Security Update for python3-tornado: Denial of Service Vulnerability
Summary
ALSA-2026:82041: Important: python-tornado security update. Affects python3-tornado versions < 6.5.10-1.el10_2.1. Fixed in 6.5.10-1.el10_2.1. How to fix ↓
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Background
Python3-tornado is a powerful web framework and asynchronous networking library for Python, designed to handle thousands of simultaneous connections efficiently. It is widely used for building web applications and services that require long-lived network connections. However, it has been found to be vulnerable to a Denial of Service (DoS) attack due to a decompression bomb issue in its CurlAsyncHTTPClient component.
Vulnerability Detail
The vulnerability identified as CVE-2026-103262 allows attackers to exploit the CurlAsyncHTTPClient in python3-tornado by sending specially crafted requests that trigger excessive resource consumption. This can lead to a Denial of Service, making the application unresponsive and potentially crashing the server. The issue arises from the handling of decompression bombs, which are files designed to expand significantly when decompressed, consuming large amounts of memory and CPU resources.
How To Fix
Minimum fixed version
6.5.10-1.el10_2.1
This is the first release that contains the fix.
sudo dnf update python3-tornadoTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, you can implement rate limiting on incoming requests to the CurlAsyncHTTPClient to mitigate the risk of a DoS attack. This can be done by configuring your web server or application to limit the number of requests from a single IP address within a specified time frame.
Conclusion
The python3-tornado package has a critical vulnerability that can lead to Denial of Service attacks. It is essential to update to the latest version to protect your application. Utilizing tools like Vulert can help you monitor for such vulnerabilities effectively.
See every vulnerability recorded for python3-tornado →
FAQ
A decompression bomb is a file that is intentionally crafted to expand significantly when decompressed, consuming excessive system resources and potentially leading to a Denial of Service.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in your software. By uploading your manifest file like package-lock.json to Vulert's playground, you can check for vulnerabilities without any signup.
If exploited, this vulnerability can lead to a Denial of Service, causing your application to become unresponsive and potentially crashing the server, affecting all users.
Using an outdated version of python3-tornado exposes your application to security risks. It is highly recommended to update to the latest patched version to protect against known vulnerabilities.
If immediate updates are not possible, consider implementing rate limiting and monitoring your application for unusual traffic patterns to mitigate the risk of exploitation.
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