A deeply nested document will cause the shell to hang. I'm not totally sure it is just the shell, as all CPUs spin and my system hangs. (Keep that in mind while testing).

I've provided a mongo wire message encoded as a file that can be netcat'ed into the server. Then a supplemental query to the collection will cause the shell (and in my case, entire system, including mouse/video/etc) to hang.

The test document that is inserted is just under 16Mb in size, with recursive documents {'': {'': ...}}. Basically large enough to cause any recursive bson parser to stack overflow.