Moderate Vulnerability in python3-idna: Denial of Service Risk
Summary
ALSA-2026:54481: Moderate: python-idna security update. Affects python3-idna versions < 3.7-6.el10_2. Fixed in 3.7-6.el10_2. How to fix ↓
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Background
Python3-idna is a library that provides support for the Internationalized Domain Names in Applications (IDNA) protocol, allowing Python applications to handle domain names with non-ASCII characters. This library is crucial for applications that need to interact with internationalized web resources. However, it is susceptible to vulnerabilities that can compromise the stability and security of applications relying on it.
Vulnerability Detail
The vulnerability identified as CVE-2026-45409 in python-idna allows for a Denial of Service (DoS) attack through specially crafted long inputs. An attacker can exploit this vulnerability by sending excessively long input strings to the application, which may lead to resource exhaustion and potentially crash the application. This vulnerability poses a significant risk to any application that utilizes the python3-idna library, as it can disrupt service availability and degrade user experience.
How To Fix
Minimum fixed version
3.7-6.el10_2
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
If immediate patching is not feasible, consider implementing input validation to restrict the length of inputs processed by the application. This can help mitigate the risk of a DoS attack by preventing excessively long inputs from being processed.
Conclusion
The python3-idna library has a moderate vulnerability (CVE-2026-45409) that can lead to Denial of Service attacks through long input strings. It is crucial to update to the patched version (3.7-6.el10_2) to mitigate this risk. If immediate updates are not possible, consider implementing input validation as a temporary measure.
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FAQ
CVE-2026-45409 is a security vulnerability in the python-idna library that allows for Denial of Service attacks through specially crafted long inputs.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The vulnerability can lead to service disruptions, application crashes, and degraded user experience due to resource exhaustion.
Yes, the patched version of python3-idna is 3.7-6.el10_2. Updating to this version will resolve the vulnerability.
Implement input validation to restrict the length of inputs processed by your application as a temporary workaround.
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