CVE-2021-32040

It may be possible to have an extremely long aggregation pipeline in
conjunction with a specific stage/operator and cause a stack overflow due
to the size of the stack frames used by that stage. If an attacker could
cause such an aggregation to occur, they could maliciously crash MongoDB in
a DoS attack. This vulnerability affects MongoDB Server v4.4 versions prior
to and including 4.4.28, MongoDB Server v5.0 versions prior to 5.0.4 and
MongoDB Server v4.2 versions prior to 4.2.16. Workaround: >= v4.2.16 users
and all v4.4 users can add the --setParameter
internalPipelineLengthLimit=50 instead of the default 1000 to mongod at
startup to prevent a crash.