We’ve found a new vulnerability in a Zend Framework 1 and 2 email component used by all Magento 1 and Magento 2 software (as well as other PHP solutions). This vulnerability is serious and can lead to a remote code execution attack if your servers use Sendmail as a mail transport agent. Learn how to protect your sites at https://magento.com/security/news/new-zend-framework-1-security-vulnerability

