ntpd in NTP before 4.2.8p9, when running on Windows, allows remote attackers to cause a denial of service via a large UDP packet.
https://www.kb.cert.org/vuls/id/633847
https://bto.bluecoat.com/security-advisory/sa139
http://www.securitytracker.com/id/1037354
http://www.securityfocus.com/bid/94450
http://support.ntp.org/bin/view/Main/SecurityNotice#Recent_Vulnerabilities