The Sigma Forms Pro plugin for WordPress is vulnerable to Remote Code Execution in all versions up to, and including, 1.4.5 via the handleformsubmission function. This is due to the plugin dynamically granting the unfilteredupload capability to all users during form submissions and bypassing MIME type validation when allowedfiletypes is not configured. This makes it possible for unauthenticated attackers to execute code on the server. Several default pre-built templates including Job Application, Support Ticket, and Wholesale Application have file upload fields with no file type restrictions configured by design, making this vulnerability immediately exploitable upon installation.