The Hash Form – Drag & Drop Form Builder plugin for WordPress is vulnerable to limited file uploads due to a misconfigured file type validation in the 'handleUpload' function in all versions up to, and including, 1.1.9. This makes it possible for unauthenticated attackers to upload files that are excluded from both the 'allowedExtensions' and 'unallowed_extensions' arrays on the affected site's server, including files that may contain cross-site scripting.