PowerDNS (aka pdns) Authoritative Server before 3.4.10 allows remote attackers to cause a denial of service (backend CPU consumption) via a long qname.
https://github.com/PowerDNS/pdns/commit/881b5b03a590198d03008e4200dd00cc537712f3
https://doc.powerdns.com/md/security/powerdns-advisory-2016-01/
http://www.securitytracker.com/id/1036761
http://www.securityfocus.com/bid/92917