ISC BIND 9.4.x 9.5.x 9.6.x and 9.7.x before 9.7.6-P2; 9.8.x before 9.8.3-P2; 9.9.x before 9.9.1-P2; and 9.6-ESV before 9.6-ESV-R7-P2 when DNSSEC validation is enabled does not properly initialize the failing-query cache which allows remote attackers to cause a denial of service (assertion failure and daemon exit) by sending many queries.