It was discovered that PHPMailer, a popular library to send email from PHP applications, allowed a remote attacker to execute code if they were able to provide a crafted Sender address (CVE-2016-10033).
It was discovered that PHPMailer prior to 5.2.22 contained a local file
disclosure vulnerability if content passed to msgHTML()
was sourced
from unfiltered user input (CVE-2017-5223).