A remote code execution vulnerability has been found in the Swift Mailer library (swiftmailer/swiftmailer) recently. See this advisory for details. If you are not using the default mail() transport, this particular problem does not affect you. Upgrading is of course still recommended!

References

• https://github.com/FriendsOfPHP/security-advisories/blob/master/neos/swiftmailer/2017-01-06.yaml
• https://www.neos.io/blog/flow-sa-2017-01.html