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.