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Vulnerability · Published Mar 5, 2026 · Assigned by GitHub_M

CVE-2026-28350lxml_html_clean: <base> tag injection through default Cleaner configuration

Medium 6.1

In plain English

A medium-severity security flaw in lxml_html_clean from fedora-python. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.1Medium
Exploit odds (30 days)0.3%top 77.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

lxml_html_clean is a project for HTML cleaning functionalities copied from `lxml.html.clean`. Prior to version 0.4.4, the <base> tag passes through the default Cleaner configuration. While page_structure=True removes html, head, and title tags, there is no specific handling for <base>, allowing an attacker to inject it and hijack relative links on the page. This issue has been patched in version 0.4.4.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12lxml4.9.2-1+deb12u1DEBIAN-CVE-2026-28350
Debian:13lxml5.2.0-1DEBIAN-CVE-2026-28350
Debian:14lxml5.2.0-1DEBIAN-CVE-2026-28350
Debian:13lxml-html-clean0.4.4-1~deb13u1DEBIAN-CVE-2026-28350
Debian:14lxml-html-clean0.4.4-1DEBIAN-CVE-2026-28350
PyPIlxml-html-clean0.4.4GHSA-xvp8-3mhv-424c
PyPIlxml-html-clean0.4.4PYSEC-2026-2202
Ubuntu:24.04:LTSlxml-html-cleanno fix listedUBUNTU-CVE-2026-28350
Ubuntu:25.10lxml-html-cleanno fix listedUBUNTU-CVE-2026-28350
Ubuntu:26.04:LTSlxml-html-cleanno fix listedUBUNTU-CVE-2026-28350
Ubuntu:26.10lxml-html-cleanno fix listedUBUNTU-CVE-2026-28350

Affected products (as reported)

VendorProductVersions
fedora-python lxml_html_clean < 0.4.4

Weakness: CWE-116 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

References