The handle_regservice_request function in mDNSResponder before 625.41.2 allows remote attackers to execute arbitrary code or cause a denial of service (NULL pointer dereference) via unspecified vectors.
https://support.apple.com/HT206846
http://www.securitytracker.com/id/1036181
http://www.oracle.com/technetwork/topics/security/bulletinjul2016-3090568.html