CVE-2024-52595 is a high-severity (CVSS 7.7) Cross-site Scripting (XSS) vulnerability in lxml-html-clean. A fix is available for lxml-html-clean — see the affected versions and patch details below.
HTML Cleaner allows crafted scripts in special contexts like svg or math to pass through
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-52595.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
lxml-html-cleanReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
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>.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | lxml-html-clean | all versions | 0.4.0pip install --upgrade 'lxml-html-clean==0.4.0' |
Affected Products
lxml html cleanfedoralovespythonDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lxml-html-clean, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update lxml-html-clean to 0.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-52595 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2024-52595 in your dependencies?
Find it across PyPI, including transitive dependencies.