HTMLSanitizer.jl is a Whitelist-based HTML sanitizer. Prior to version 0.2.1, when adding the style tag to the whitelist, content inside the tag is incorrectly unescaped, and closing tags injected as content are interpreted as real HTML, enabling tag injection and JavaScript execution. This could result in possible cross-site scripting (XSS) in any HTML that is sanitized with this library. This issue has been patched in version 0.2.1. A workaround involves adding the math and svg elements to the whitelist manually.
HTMLSanitizer.jl Possible XSS