Moderate Vulnerability in python3-idna: Denial of Service Risk from Long Inputs
Summary
ALSA-2026:54484: Moderate: python-idna security update. Affects python3-idna versions < 2.10-8.el9_8. Fixed in 2.10-8.el9_8. How to fix ↓
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Background
Python is a widely-used interpreted programming language known for its object-oriented features, dynamic typing, and extensive libraries. The python3-idna package is a library that implements the Internationalized Domain Names in Applications (IDNA) protocol, allowing for the use of non-ASCII characters in domain names. This package is crucial for applications that require internationalization support. However, it has been identified to have a vulnerability that can lead to Denial of Service (DoS) attacks when processing specially crafted long inputs.
Vulnerability Detail
The vulnerability in python3-idna, identified as CVE-2026-45409, allows an attacker to exploit the package by sending specially crafted long inputs. This can lead to a Denial of Service condition, where the application becomes unresponsive or crashes due to excessive resource consumption. The issue arises from improper handling of input lengths, which can overwhelm the system's processing capabilities, potentially affecting availability and user experience.
How To Fix
Minimum fixed version
2.10-8.el9_8
This is the first release that contains the fix.
sudo dnf update python3-idnaTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, you can implement input validation to limit the length of inputs processed by the python3-idna package. This can help mitigate the risk of a Denial of Service attack until the package is updated. For example, you can restrict input length in your application code as follows:
if len(user_input) > MAX_LENGTH: raise ValueError('Input too long')
Conclusion
The python3-idna package has a moderate vulnerability that can lead to Denial of Service attacks through specially crafted long inputs. It is crucial to update to the patched version to mitigate this risk. Additionally, implementing input validation can serve as a temporary workaround until the update is applied.
See every vulnerability recorded for python3-idna →
FAQ
The vulnerability allows for Denial of Service attacks via specially crafted long inputs.
You can use the Vulert platform to check if your application is affected by this vulnerability without needing to install any software.
The primary impact is the possibility of Denial of Service, which can render your application unresponsive.
Yes, a patched version of python3-idna is available. Update to version 2.10-8.el9_8 or later.
Vulert monitors open-source vulnerabilities in your software using a manifest file like package-lock.json, providing real-time alerts.
Related vulnerabilities
Recent vulnerabilities recorded for python3-idna.
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