A Cross-site Scripting (XSS) vulnerability was found in the python-lxml's clean module. The module's parser did not properly imitate browsers, causing different behaviors between the sanitizer and the user's page. This flaw allows a remote attacker to run arbitrary HTML/JS code. The highest threat from this vulnerability is to confidentiality and integrity.

Incomplete blacklist vulnerability in the lxml.html.clean module in lxml before 3.3.5 allows remote attackers to conduct cross-site scripting (XSS) attacks via control characters in the link scheme to the cleanhtml function.