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.
https://plugins.trac.wordpress.org/browser/wp-sendgrid-mailer/trunk/wp-sendgrid-mailer.php#L167
https://plugins.svn.wordpress.org/wp-sendgrid-mailer/tags/1.4/wp-sendgrid-mailer.php