Buffer overflow in Citadel SMTP server 7.10 and earlier allows remote attackers to execute arbitrary code via a long RCPT TO command, which is not properly handled by the makeuserkey function. NOTE: some of these details were obtained from third party information.
http://secunia.com/advisories/28590
https://exchange.xforce.ibmcloud.com/vulnerabilities/39807
https://www.exploit-db.com/exploits/4949