CVE-2019-6477

With pipelining enabled each incoming query on a TCP connection requires a
similar resource allocation to a query received via UDP or via TCP without
pipelining enabled. A client using a TCP-pipelined connection to a server
could consume more resources than the server has been provisioned to
handle. When a TCP connection with a large number of pipelined queries is
closed, the load on the server releasing these multiple resources can cause
it to become unresponsive, even for queries that can be answered
authoritatively or from cache. (This is most likely to be perceived as an
intermittent server problem).

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