Pie Register < 3.8.3.3 - Unauthenticated Arbitrary File Upload

Description

The plugin is vulnerable to arbitrary file uploads due to missing file type validation in the pie_save_registration function. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible. NOTE: This vulnerability presents itself when the 'Anyone can register' option is enabled in options-general and the 'Upload File' field is added to the registration form.