Upgrade to the latest BIND patch level:

Prevents a crash when queried for a record whose RDATA exceeds
65535 bytes.

Prevents a crash when validating caused by using "Bad cache" data
before it has been initialized.

ISC_QUEUE handling for recursive clients was updated to address
a race condition that could cause a memory leak. This rarely
occurred with UDP clients, but could be a significant problem
for a server handling a steady rate of TCP queries.

A condition has been corrected where improper handling of
zero-length RDATA could cause undesirable behavior, including
termination of the named process.

For more information: https://kb.isc.org/article/AA-00788