A deliberately constructed packet can exploit an error in the handling of queries for TKEY records, permitting denial of service
Both recursive and authoritative servers are vulnerable to this defect. Additionally, exposure is not prevented by either ACLs or configuration options limiting or denying service because the exploitable code occurs early in the packet handling, before checks enforcing those boundaries.
All versions of BIND 9 from BIND 9.1.0 (inclusive) through BIND 9.9.7-P1 and BIND 9.10.2-P2 are vulnerable.
Operators should take steps to upgrade to a patched version as soon as possible.