A denial of service flaw was found in the way BIND handled query requests when using DNS64 with “break-dnssec yes” option. A remote attacker could use this flaw to make named exit unexpectedly with an assertion failure via a specially crafted DNS request.
Servers which have configurations which require DNS64 and "break-dnssec yes;" should upgrade. Servers which are not using these features in conjunction are not at risk from this defect.