The Editorial Assistant by Sovrn plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the 'ajax_zemanta_set_featured_image' function in versions up to, and including, 1.3.3. This makes it possible for authenticated attackers, with subscriber-level access and above, to upload attachment files (such as jpg, png, txt, zip), and set the post featured image.
https://plugins.trac.wordpress.org/browser/zemanta/tags/1.3.3/zemanta.php#L713