Auto Featured Image <= 4.2.1 - Missing Authorization to Authenticated (Contributor+) Post Thumbnail Modification

The Auto Featured Image (Auto Post Thumbnail) plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the bulk_action_generate_handler function in all versions up to, and including, 4.2.1. This makes it possible for authenticated attackers, with Contributor-level access and above, to delete or generate featured images on posts they do not own.