CVE-2021-20330

An attacker with basic CRUD permissions on a replicated collection can run the applyOps command with specially malformed oplog entries, resulting in a potential denial of service on secondaries. This issue affects MongoDB Server v4.0 versions prior to 4.0.25; MongoDB Server v4.2 versions prior to 4.2.14; MongoDB Server v4.4 versions prior to 4.4.6.

Source: CVE-2021-20330