Improper Encoding or Escaping of Output Affecting lxml-html-clean package, versions [,0.4.4)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-LXMLHTMLCLEAN-15369131
- published3 Mar 2026
- disclosed2 Mar 2026
- credituug4na
Introduced: 2 Mar 2026
CVE-2026-28350 (opens in a new tab)How to fix?
Upgrade lxml-html-clean to version 0.4.4 or higher.
Overview
lxml-html-clean is a HTML cleaner from lxml project
Affected versions of this package are vulnerable to Improper Encoding or Escaping of Output in the default Cleaner configuration due to the incomplete page_structure kill set that does not account for <base> tags outside <head> tags. An attacker can hijack the resolution of all relative URLs, redirect user navigation and form submissions, steal credentials or sensitive data, execute malicious scripts, or alter the appearance of the page by injecting a <base> tag and controlling the base URL for links, scripts, images, and stylesheets.
PoC
from lxml_html_clean import clean_html
# The base tag is preserved in the output
result = clean_html('<base href="http://evil.com/"><a href="/account">Account</a>')
print(result)
# Output: <div><base href="http://evil.com/">...<a href="/account">Account</a></div>