Kerio WinRoute Firewall before 6.2.1 allows remote attackers to cause a denial of service (application crash) via unknown vectors in the "email protocol inspectors," possibly (1) SMTP and (2) POP3.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26263
http://www.vupen.com/english/advisories/2006/1677
http://www.securityfocus.com/bid/17859
http://www.securityfocus.com/archive/1/433585/100/0/threaded
http://www.kerio.com/kwf_history.html