Cure53 DOMPurify before 2.0.17 allows mutation XSS. This occurs because a serialize-parse roundtrip does not necessarily return the original DOM tree, and a namespace can change from HTML to MathML, as demonstrated by nesting of FORM elements.
Upgrade to version 2.0.17 or later.
publishedAdvisory PublishedDec 18th, 2020
reportedReported by AnonymousDec 18th, 2020