CVE-2024-52595 HTML Cleaner allows crafted scripts in special contexts like svg or math to pass through

What is CVE-2024-52595?

CVE-2024-52595 is a high-severity cross-site scripting vulnerability in fedora-python lxml_html_clean, published on 19 Nov 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

lxml_html_clean is a project for HTML cleaning functionalities copied from `lxml.html.clean`. Prior to version 0.4.0, the HTML Parser in lxml does not properly handle context-switching for special HTML tags such as `<svg>`, `<math>` and `<noscript>`. This behavior deviates from how web browsers parse and interpret such tags. Specifically, content in CSS comments is ignored by lxml_html_clean but may be interpreted differently by web browsers, enabling malicious scripts to bypass the cleaning process. This vulnerability could lead to Cross-Site Scripting (XSS) attacks, compromising the security of users relying on lxml_html_clean in default configuration for sanitizing untrusted HTML content. Users employing the HTML cleaner in a security-sensitive context should upgrade to lxml 0.4.0, which addresses this issue. As a temporary mitigation, users can configure lxml_html_clean with the following settings to prevent the exploitation of this vulnerability. Via `remove_tags`, one may specify tags to remove - their content is moved to their parents' tags. Via `kill_tags`, one may specify tags to be removed completely. Via `allow_tags`, one may restrict the set of permissible tags, excluding context-switching tags like `<svg>`, `<math>` and `<noscript>`.

Weakness: CWE-83, CWE-79, CWE-184

Which versions are affected by CVE-2024-52595?

3 open source packages ship an affected version, including lxml-html-clean. It affects 1 product.

Products include Fedoralovespython Lxml Html Clean.

How do I fix CVE-2024-52595?

Upgrade lxml-html-clean to 0.4.0 or later.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2024-52595 being exploited?

There is no known exploitation of CVE-2024-52595 in the wild and no public exploit code.

Other vulnerabilities in fedora-python lxml_html_clean

• CVE-2026-28348 lxml_html_clean: CSS @import Filter Bypass via Unicode Escapes Medium 6.1
• CVE-2026-28350 lxml_html_clean: <base> tag injection through default Cleaner configuration Medium 6.1

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2024-52595, GHSA-5jfw-gq64-q45f, PYSEC-2024-160, UBUNTU-CVE-2024-52595.