Crypto-NAK packets in ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote attackers to bypass authentication.
https://security.netapp.com/advisory/ntap-20171004-0001/
https://security.gentoo.org/glsa/201607-15
https://security.gentoo.org/glsa/201604-03
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05270839
https://cert-portal.siemens.com/productcert/pdf/ssa-497656.pdf
https://bugzilla.redhat.com/show_bug.cgi?id=1274265
http://www.securitytracker.com/id/1033951
http://www.securityfocus.com/bid/77287