In BIND 9.0.0 - 9.11.21, 9.12.0 - 9.16.5, 9.17.0 - 9.17.3, also affects 9.9.3-S1 - 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker on the network path for a TSIG-signed request, or operating the server receiving the TSIG-signed request, could send a truncated response to that request, triggering an assertion failure, causing the server to exit. Alternately, an off-path attacker would have to correctly guess when a TSIG-signed request was sent, along with other characteristics of the packet and message, and spoof a truncated response to trigger an assertion failure, causing the server to exit.