CVE-2016-10045 (phpmailer)
The isMail transport in PHPMailer before 5.2.20, when the Sender property is not set, might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code by leveraging improper interaction between the escapeshellarg function and internal escaping performed in the mail function. NOTE: this vulnerability exists because of an incorrect fix for CVE-2016-10033.
Source: CVE-2016-10045 (phpmailer)