CVE-2026-28350: lxml-html-clean has <base> tag injection through default Cleaner configuration

March 2, 2026 (updated March 5, 2026)

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.

References

github.com/advisories/GHSA-xvp8-3mhv-424c
github.com/fedora-python/lxml_html_clean
github.com/fedora-python/lxml_html_clean/commit/9c5612ca33b941eec4178abf8a5294b103403f34
github.com/fedora-python/lxml_html_clean/security/advisories/GHSA-xvp8-3mhv-424c
nvd.nist.gov/vuln/detail/CVE-2026-28350

Code Behaviors & Features

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