Critical Denial of Service Vulnerability in python-tornado
Summary
RLSA-2026:82041: Important: python-tornado security update. Affects python-tornado versions < 0:6.5.10-1.el10_2.1. Fixed in 0:6.5.10-1.el10_2.1. How to fix ↓
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Background
Python-tornado is an asynchronous networking library designed to handle thousands of simultaneous connections efficiently. It is widely used for building web applications and services that require long-lived connections, such as WebSockets. The library provides a robust framework for handling HTTP requests and responses, making it a popular choice for developers. However, it is susceptible to a Denial of Service (DoS) attack due to a vulnerability in the CurlAsyncHTTPClient component, which can be exploited through decompression bombs.
Vulnerability Detail
The vulnerability, identified as CVE-2026-103262, allows an attacker to craft a specially designed input that, when processed by the CurlAsyncHTTPClient, can lead to excessive resource consumption. This can result in a Denial of Service condition, where legitimate users are unable to access the service due to resource exhaustion. The issue arises from the handling of compressed data, where the decompression process can consume an inordinate amount of memory and CPU resources, effectively crashing the service.
How To Fix
Minimum fixed version
0:6.5.10-1.el10_2.1
This is the first release that contains the fix.
sudo dnf update python-tornadoTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If immediate updating is not possible, consider implementing rate limiting on incoming requests to mitigate the impact of potential DoS attacks. Additionally, monitor resource usage closely to identify any unusual patterns that may indicate an ongoing attack.
Conclusion
In summary, the python-tornado package has a critical vulnerability that can lead to Denial of Service attacks. It is crucial to update to the latest patched version to safeguard your applications. Additionally, employing workarounds such as rate limiting can help mitigate risks until the update can be applied.
See every vulnerability recorded for python-tornado →
FAQ
A Denial of Service attack is a malicious attempt to disrupt the normal functioning of a targeted server, service, or network by overwhelming it with a flood of traffic or resource-intensive requests.
You can check if your application is affected by this vulnerability using the Vulert playground at Vulert Scanner, which allows you to monitor and alert for open-source vulnerabilities without requiring any installation.
The primary consequence of this vulnerability is the potential for service outages, which can lead to loss of availability for users and can impact business operations.
While updating to the patched version is the best way to prevent exploitation, implementing rate limiting and monitoring resource usage can help mitigate the risk.
The CVSS score for this vulnerability is 7.5, indicating a high level of severity.
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