ASA-2019-00234 – BIND: Limiting simultaneous TCP clients is ineffective

By design, BIND is intended to limit the number of TCP clients that can be connected at any given time. The number of allowed connections is a tunable parameter which, if unset, defaults to a conservative value for most servers. Unfortunately, the code which was intended to limit the number of simultaneous connections contains an error which can be exploited to grow the number of simultaneous connections beyond this limit.