ntpq in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to cause a denial of service (crash) via crafted mode 6 response packets.
https://security.netapp.com/advisory/ntap-20171004-0001/
https://security.gentoo.org/glsa/201607-15
http://www.securitytracker.com/id/1033951
http://www.securityfocus.com/bid/77288
http://www.oracle.com/technetwork/topics/security/linuxbulletinapr2016-2952096.html
http://www.debian.org/security/2015/dsa-3388
http://support.ntp.org/bin/view/Main/NtpBug2919