A malicious client can send many DNS messages over TCP, potentially causing the server to become unstable while the attack is in progress. The server may recover after the attack ceases. Use of ACLs will not mitigate the attack. This issue affects BIND 9 versions 9.18.1 through 9.18.27, 9.19.0 through 9.19.24, and 9.18.11-S1 through 9.18.27-S1.
Solution:
Workaround:
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.