Moderate Vulnerability in python3-idna: Denial of Service Risk
Summary
ALSA-2026:54290: Moderate: python-idna security update. Affects python3-idna versions < 2.5-8.el8_10. Fixed in 2.5-8.el8_10. How to fix ↓
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Background
Python is a widely-used interpreted programming language known for its versatility and ease of use. The python3-idna package is a library that handles Internationalized Domain Names (IDN) in Python, allowing for the use of non-ASCII characters in domain names. This package is essential for applications that require domain name resolution in various languages. However, it has been identified to have a vulnerability that could lead to a Denial of Service (DoS) attack when processing specially crafted long inputs.
Vulnerability Detail
The vulnerability identified as CVE-2026-45409 affects the python3-idna package, allowing an attacker to exploit the library by sending specially crafted long inputs. This could lead to a Denial of Service condition, where the application becomes unresponsive or crashes, impacting the availability of services that rely on this package. The issue arises from inadequate input validation, which fails to handle excessively long strings appropriately.
How To Fix
Minimum fixed version
2.5-8.el8_10
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 an immediate update is not feasible, consider implementing input validation in your application to limit the length of inputs processed by the python3-idna library. This can help mitigate the risk of a Denial of Service attack until the package is updated.
Conclusion
The python3-idna package has a moderate vulnerability that could lead to Denial of Service attacks through specially crafted inputs. It is crucial to update to the patched version to mitigate this risk. In the meantime, implementing input validation can serve as a temporary measure to protect your application.
See every vulnerability recorded for python3-idna →
FAQ
CVE-2026-45409 is a vulnerability in the python3-idna package 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 needing to sign up.
The main consequence is a potential Denial of Service, where the application may become unresponsive or crash, affecting service availability.
Yes, the patched version of python3-idna is 2.5-8.el8_10. Updating to this version will resolve the vulnerability.
Implement input validation to limit the length of inputs processed by the python3-idna library as a temporary workaround.
Related vulnerabilities
Recent vulnerabilities recorded for python3-idna.
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