Envolve Plugin <= 1.0 - Unauthenticated Arbitrary File Upload via language_file and fonts_file

The Envolve Plugin plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the 'zetra_languageUpload' and 'zetra_fontsUpload' functions in all versions up to, and including, 1.0. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.