The default configuration of ISC BIND before 9.4.1-P1, when configured as a caching name server, allows recursive queries and provides additional delegation information to arbitrary IP addresses, which allows remote attackers to cause a denial of service (traffic amplification) via DNS queries with spoofed source IP addresses.
An "incorrect assumption" in the authvalidated validator function in BIND 9.3.0, when DNSSEC is enabled, allows remote attackers to cause a denial of service (named server exit) via crafted DNS packets that cause an internal consistency test (self-check) to fail.