An issue was discovered in Repute ARForms 3.5.1 and prior. An attacker is able to delete any file on the server with web server privileges by sending a malicious request to admin-ajax.php.
https://wpvulndb.com/vulnerabilities/9139
https://euvd.enisa.europa.eu/vulnerability/EUVD-2018-7676
http://packetstormsecurity.com/files/149981/WordPress-Arforms-3.5.1-Arbitrary-File-Delete.html