SendGrid for WordPress <= 1.4 - Missing Authorization to Authenticated (Subscriber+) Log Deletion

The SendGrid for WordPress plugin for WordPress is vulnerable to unauthorized loss of data due to a missing capability check on the 'wp_mailplus_clear_logs' function in all versions up to, and including, 1.4. This makes it possible for authenticated attackers, with Subscriber-level access and above, to delete the plugin's log files.