Verification SMS with TargetSMS <= 1.5 - Unauthenticated Limited Remote Code Execution

The Verification SMS with TargetSMS plugin for WordPress is vulnerable to limited Remote Code Execution in all versions up to, and including, 1.5 via the 'targetvr_ajax_handler' function. This is due to a lack of validation on the type of function that can be called. This makes it possible for unauthenticated attackers to execute any callable function on the site, such as phpinfo().