ApostropheCMS is an open-source Node.js content management system, and sanitize-html provides a simple HTML sanitizer with a clear API. Under the default configuration, versions of sanitize-html prior to 2.17.4 can turn attacker-controlled content inside a disallowed xmp element into live HTML or JavaScript. This is a sanitizer bypass in the default disallowedTagsMode: 'discard' path and can lead to stored XSS in applications that render sanitized output back to users. Version 2.17.4 patches the issue.