Medium severity · published Mar 5, 2026
CVE-2026-28348
lxml_html_clean: CSS @import Filter Bypass via Unicode Escapes
6.1
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 16% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LX
lxml_html_clean · fedora-python
< 0.4.4 · source: vendor
LH
Lxml Html Clean · Fedoralovespython
before 0.4.4 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-28348
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-28348
Patch
https://github.com/fedora-python/lxml_html_clean/commit/2ef732667ddbc74ea59847bcf24b75809aaeed3b
Exploit
https://github.com/fedora-python/lxml_html_clean/security/advisories/GHSA-hw26-mmpg-fqfg
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8.2
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6.1
CVE-2026-28350
lxml_html_clean: <base> tag injection through default Cleaner configuration