The query_findclosestnsec3 function in query.c in named in ISC BIND 9.6, 9.7, and 9.8 before 9.8.6-P2 and 9.9 before 9.9.4-P2, and 9.6-ESV before 9.6-ESV-R10-P2, allows remote attackers to cause a denial of service (INSIST assertion failure and daemon exit) via a crafted DNS query to an authoritative nameserver that uses the NSEC3 signing feature.