HT Contact Form <= 2.8.2 - Unauthenticated Stored Cross-Site Scripting via File Upload Field

The HT Contact Form – Drag & Drop Form Builder for WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'file_upload' parameter in all versions up to, and including, 2.8.2 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Exploitation requires the 'Store Submissions' setting to be enabled, as this controls whether unsanitized field values are persisted to the database and subsequently rendered via dangerouslySetInnerHTML in the admin entry viewer.