Moderate: python-lxml security update

python3-lxml Updated 02 Oct 2025

Summary

09/11/2021

Disclosed on

N/A

Severity

Yes i

Fix available

Unrated

Severity

Not published

CVSS Score

ALSA-2021:4158: Moderate: python-lxml security update. Affects python3-lxml versions < 4.2.3-3.el8. Fixed in 4.2.3-3.el8. How to fix ↓

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Background

python-lxml is an XML processing library that provides access to libxml2 and libxslt libraries using the Python ElementTree API. It is widely used for parsing and manipulating XML data in Python applications. The library is an essential component for applications that require XML processing capabilities.

Vulnerability Detail

The vulnerability (CVE-2021-28957) in python-lxml is related to missing input sanitization for formaction HTML5 attributes, which can lead to cross-site scripting (XSS) attacks. An attacker can exploit this vulnerability by injecting malicious code into the formaction attribute, which will be executed when the user interacts with the affected HTML form. This can result in the execution of arbitrary JavaScript code in the context of the victim's browser, potentially leading to unauthorized actions or data theft.

How To Fix

Minimum fixed version

4.2.3-3.el8

This is the first release that contains the fix.

sudo dnf update python3-lxml

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Conclusion

In conclusion, the python-lxml library is vulnerable to a cross-site scripting (XSS) attack due to missing input sanitization for formaction HTML5 attributes. To mitigate this vulnerability, it is crucial to update the python3-lxml package to version 4.2.3-3.el8 or later. This update includes the necessary fixes to prevent XSS attacks. For further support on vulnerability remediation, you can contact DevNack.com.

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FAQ

What is python-lxml?

python-lxml is an XML processing library for Python that provides access to libxml2 and libxslt libraries. It allows developers to parse, manipulate, and generate XML data using the Python ElementTree API.

What is the impact of this vulnerability?

The vulnerability in python-lxml can allow an attacker to execute arbitrary JavaScript code in the context of a victim's browser. This can lead to unauthorized actions, data theft, or further exploitation of the affected system.

How can I check if my system is affected?

You can check if your system is affected by using the Vulert Playground at Vulert Scanner. Simply upload your manifest file (e.g., package-lock.json) to the playground, and it will analyze and alert you if your application is affected by this vulnerability.

Is there a workaround available for this vulnerability?

No specific workaround is mentioned for this vulnerability. It is recommended to update the python3-lxml package to the latest version to mitigate the risk.