The Webform module fails to properly force the download of certain uploaded file types when they are served. In specific site configurations, a file uploaded via a webform can be rendered inline by a browser, leading to cross-site scripting (XSS), where malicious scripts are executed in the victim's browser. Approximately 436,300 instances were identified globally. This issue requires a user with permissions to create or edit webforms to allow the affected file extensions, and a victim must manually open the uploaded file.