The 3D FlipBook, PDF Viewer, PDF Embedder – Real 3D FlipBook WordPress Plugin plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the 'r3dfb_save_thumbnail_callback' function in all versions up to, and including, 4.6. This makes it possible for authenticated attackers, with Author-level access and above, to upload arbitrary files on the affected site's server which may make remote code execution possible.