The STARTTLS implementation in Kerio Connect 7.1.4 build 2985 and MailServer 6.x does not properly restrict I/O buffering which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place related to a \plaintext command injection\ attack a similar issue to CVE-2011-0411. NOTE: some of these details are obtained from third party information.