The Email Subscribers by Icegram Express plugin for WordPress is vulnerable to unauthorized access of data, modification of data, and loss of data due to a missing capability check on the handle_ajax_request function in all versions up to, and including, 5.7.19. This makes it possible for authenticated attackers, with subscriber-level access and above, to cause a loss of confidentiality, integrity, and availability, by performing multiple unauthorized actions. Some of these actions could also be leveraged to conduct PHP Object Injection and SQL Injection attacks.