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CVE-2026-28348— lxml_html_clean: CSS @import Filter Bypass via Unicode Escapes

Quick assessment

Affected
fedora-python lxml_html_clean
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

lxml_html_clean是Fedora Python SIG开源的一个从 lxml.HTML.clean 复制的 HTML 清理功能的单独项目。 lxml_html_clean 0.4.4之前版本存在安全漏洞，该漏洞源于_has_sneaky_javascript方法在检查危险CSS关键字前剥离反斜杠，可能导致CSS Unicode转义序列绕过过滤器。

CVSS 6.1 · Medium EPSS 0.28% · P21
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I. Basic Information for CVE-2026-28348

Vulnerability Information
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Vulnerability Title
lxml_html_clean: CSS @import Filter Bypass via Unicode Escapes
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对输出编码和转义不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
lxml_html_clean 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
lxml_html_clean是Fedora Python SIG开源的一个从 lxml.HTML.clean 复制的 HTML 清理功能的单独项目。 lxml_html_clean 0.4.4之前版本存在安全漏洞，该漏洞源于_has_sneaky_javascript方法在检查危险CSS关键字前剥离反斜杠，可能导致CSS Unicode转义序列绕过过滤器。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
fedora-python lxml_html_clean < 0.4.4 -

II. Public POCs for CVE-2026-28348

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III. Intelligence Information for CVE-2026-28348

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Patches & Fixes for CVE-2026-28348 (1)

Vendor Advisories for CVE-2026-28348 (1)

IV. Related Vulnerabilities

Same product: lxml_html_clean
Same vendor: fedora-python
Same weakness: CWE-116