ntpd in NTP 4.2.x before 4.2.8p4, and 4.3.x before 4.3.77 allows remote authenticated users to cause a denial of service (infinite loop or crash) by pointing the key file at the log file.
https://security.netapp.com/advisory/ntap-20171004-0001/
https://security.gentoo.org/glsa/201607-15
https://bugzilla.redhat.com/show_bug.cgi?id=1274258
http://www.securitytracker.com/id/1033951
http://www.securityfocus.com/bid/77279