The Pexels: Free Stock Photos plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the 'pexels_fsp_images_options_validate' function in all versions up to, and including, 1.2.2. This makes it possible for authenticated attackers, with contributor-level and above permissions, to upload arbitrary files on the affected site's server which may make remote code execution possible.
https://plugins.trac.wordpress.org/browser/wp-pexels-free-stock-photos/trunk/settings.php#L239