Cross-site Scripting (XSS) Affecting python3-lxml package, versions <4.7.1-3.7.1


Severity

Recommended
high

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
4.03% (90th percentile)

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  • Snyk IDSNYK-SLES154-PYTHON3LXML-10115703
  • published11 May 2025
  • disclosed10 Mar 2022

Introduced: 10 Mar 2022

CVE-2021-28957  (opens in a new tab)
CWE-79  (opens in a new tab)

How to fix?

Upgrade SLES:15.4 python3-lxml to version 4.7.1-3.7.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream python3-lxml package and not the python3-lxml package as distributed by SLES. See How to fix? for SLES:15.4 relevant fixed versions and status.

An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safe_attrs_only and forms arguments, the Cleaner class does not remove the formaction attribute allowing for JS to bypass the sanitizer. A remote attacker could exploit this flaw to run arbitrary JS code on users who interact with incorrectly sanitized HTML. This issue is patched in lxml 4.6.3.

CVSS Base Scores

version 3.1