Moderate severityNVD Advisory· Published Mar 5, 2026· Updated Mar 6, 2026
lxml_html_clean: CSS @import Filter Bypass via Unicode Escapes
CVE-2026-28348
Description
lxml_html_clean is a project for HTML cleaning functionalities copied from lxml.html.clean. Prior to version 0.4.4, the _has_sneaky_javascript() method strips backslashes before checking for dangerous CSS keywords. This causes CSS Unicode escape sequences to bypass the @import and expression() filters, allowing external CSS loading or XSS in older browsers. This issue has been patched in version 0.4.4.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
lxml-html-cleanPyPI | < 0.4.4 | 0.4.4 |
Affected products
5- osv-coords4 versionspkg:apk/chainguard/label-studiopkg:pypi/lxml-html-cleanpkg:rpm/opensuse/python-lxml_html_clean&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/python-lxml_html_clean&distro=openSUSE%20Tumbleweed
< 1.22.0-r7+ 3 more
- (no CPE)range: < 1.22.0-r7
- (no CPE)range: < 0.4.4
- (no CPE)range: < 0.4.2-bp160.2.1
- (no CPE)range: < 0.4.4-1.1
- fedora-python/lxml_html_cleanv5Range: < 0.4.4
Patches
Vulnerability mechanics
References
4- github.com/advisories/GHSA-hw26-mmpg-fqfgghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-28348ghsaADVISORY
- github.com/fedora-python/lxml_html_clean/commit/2ef732667ddbc74ea59847bcf24b75809aaeed3bghsax_refsource_MISCWEB
- github.com/fedora-python/lxml_html_clean/security/advisories/GHSA-hw26-mmpg-fqfgghsax_refsource_CONFIRMWEB
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