ntpd in NTP before 4.2.8p7 and 4.3.x before 4.3.92 allows remote attackers to cause a denial of service (ntpd abort) by a large request data value, which triggers the ctl_getitem function to return a NULL value.
https://www.kb.cert.org/vuls/id/718152
http://www.securityfocus.com/bid/88204
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html