Format string vulnerability in smtp.c for smtp.proxy 1.1.3 and earlier allows remote attackers to execute arbitrary code via format string specifiers in the (1) client hostname or (2) message-id, which are injected into a syslog message.
https://exchange.xforce.ibmcloud.com/vulnerabilities/16378
http://www.securityfocus.com/bid/10509
http://secunia.com/advisories/11823
http://archives.neohapsis.com/archives/fulldisclosure/2004-06/0267.html