PYSEC-2026-2614 `lxml_html_clean.Cleaner` does not strip `javascript:` URLs from namespaced URL attributes

lxmlhtmlclean.Cleaner does not strip javascript: URLs from namespaced URL attributes xlink:href Reporter: Guillem Lefait · Date: 2026-05-10 Affected: lxml ≤ 6.1.0 and lxmlhtmlclean ≤ 0.4.4 latest stable Confirmed against: lxml 6.1.0 + lxmlhtmlclean 0.4.4 on Python 3.13.5, 3.14.4, and 3.15.0a8...

Astra Linux – Vulnerability in lxml

A XSS vulnerability was discovered in the clean module of python-lxml’s versions prior to 4.6.3. When the “safe attrsOnly” and “forms” arguments are disabled, the Cleaner class does not remove the “formaction” attribute, allowing JavaScript to bypass the sanitizer. A remote attacker could exploit...

SUSE CVE-2021-28957

An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safeattrsonly 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...

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.

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ALPINE-CVE-2021-28957

An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safeattrsonly 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...

PYSEC-2021-19

An XSS vulnerability was discovered in python-lxml's clean module versions before 4.6.3. When disabling the safeattrsonly 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...