An unauthenticated client can trigger denial of service by issuing specially crafted wire protocol messages, which cause the message decompressor to incorrectly allocate memory. This issue affects MongoDB Server v4.2 versions prior to 4.2.1; MongoDB Server v4.0 versions prior to 4.0.13; MongoDB Server v3.6 versions prior to 3.6.15 and MongoDB Server v3.4 versions prior to 3.4.24.

A user authorized to perform database queries may trigger denial of service by issuing specially crafted queries, which loop indefinitely in mathematics processing while retaining locks. This issue affects MongoDB Server v4.0 versions prior to 4.0.5; MongoDB Server v3.6 versions prior to 3.6.10 and MongoDB Server v3.4 versions prior to 3.4.19.

Incorrect scoping of kill operations in MongoDB Server's packaged SysV init scripts allow users with write access to the PID file to insert arbitrary PIDs to be killed when the root user stops the MongoDB process via SysV init. This issue affects MongoDB Server v4.0 versions prior to 4.0.11; MongoDB Server v3.6 versions prior to 3.6.14; MongoDB Server v3.4 versions prior to 3.4.22.