resolver.c in ISC BIND 9.8.5 before 9.8.5-P1, 9.9.3 before 9.9.3-P1, and 9.6-ESV-R9 before 9.6-ESV-R9-P1, when a recursive resolver is configured, allows remote attackers to cause a denial of service (assertion failure and named daemon exit) via a query for a record in a malformed zone.