HAX CMS helps manage microsite universe with PHP or NodeJs backends. Versions up to and including 26.0.0 are affected by a stored cross-site scripting (XSS) vulnerability in the "/system/api/saveNode" endpoint. An authenticated user with a permission to edit pages can bypass the HTML sanitizer by injecting an event handler attribute without whitespace before the attribute name. @haxtheweb/haxcms-nodejs 26.0.1 and haxcms-php 26.0.2 patch the issue.