|query.c in ISC BIND 9.0.x through 9.6.x, 9.4-ESV through 9.4-ESV-R5,
9.6-ESV through 9.6-ESV-R5, 9.7.0 through 9.7.4, 9.8.0 through 9.8.1,
and 9.9.0a1 through 9.9.0b1 allows remote attackers to cause a denial
of service (assertion failure and named exit) via unknown vectors
related to recursive DNS queries, error logging, and the caching of an
invalid record by the resolver.