CVE-2026-49825

lxml: javascript: URL bypass in Cleaner via xlink:href

Published Aug 20, 2026 CVSS 3.1 · 8.2 High EPSS < 1% KEV · Not listed
Description
lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in ``lxml.html.defs.link_attrs`` were missing ``xlink:href``, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4799-1 lxml security update
Github GHSA Github GHSA GHSA-4jhm-jv67-739f `lxml_html_clean.Cleaner` does not strip `javascript:` URLs from namespaced URL attributes
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Fedora-python
Fedora-python lxml Html Clean
Lxml
Lxml lxml
Vendors & Products Fedora-python
Fedora-python lxml Html Clean
Lxml
Lxml lxml
Type Values Removed Values Added
Description lxml is a library for processing XML and HTML in the Python language. Prior to 6.1.1, link attributes in ``lxml.html.defs.link_attrs`` were missing ``xlink:href``, which can be used for URL bypass attacks in embedded SVG/MathML/etc. content. This vulnerability was fixed in lxml 6.1.1 and lxml_html_clean 0.4.5.
Title lxml: javascript: URL bypass in Cleaner via xlink:href
Weaknesses CWE-184
CWE-79
References
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 21, 2026, 4:41 PM
Reserved
Jun 1, 2026, 6:50 PM
Status
Awaiting Analysis
Published
Aug 20, 2026, 3:17 PM
Modified
Oct 26, 2026, 10:10 AM
Severity
Important
Public date
Aug 20, 2026, 2:42 PM