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.

Incorrect validation of user input in the role name parser may lead to use of uninitialized memory allowing an unauthenticated attacker to use a specially crafted request to cause a denial of service. This issue affects MongoDB Server v4.4 versions prior to 4.4.0-rc12; MongoDB Server v4.2 versions prior to 4.2.9.

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.

A user authorized to perform database queries may trigger a read overrun and access arbitrary memory by issuing specially crafted queries. This issue affects MongoDB Server v4.4 versions prior to 4.4.1; MongoDB Server v4.2 versions prior to 4.2.9; MongoDB Server v4.0 versions prior to 4.0.20 and MongoDB Server v3.6 versions prior to 3.6.20.

A user authorized to perform database queries may trigger denial of service by issuing specially crafted queries which trigger an invariant in the IndexBoundsBuilder. This issue affects MongoDB Server v4.2 versions prior to 4.2.2.

A user authorized to perform database queries may trigger denial of service by issuing specially crafted queries, which use the $mod operator to overflow negative values. This issue affects: MongoDB Inc. MongoDB Server v4.4 versions prior to 4.4.1; v4.2 versions prior to 4.2.9; v4.0 versions prior to 4.0.20; v3.6 versions prior to 3.6.20.

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.

Sending specially crafted commands to a MongoDB Server may result in artificial log entries being generated or for log entries to be split. This issue affects MongoDB Server v3.6 versions prior to 3.6.20; MongoDB Server v4.0 versions prior to 4.0.21 and MongoDB Server v4.2 versions prior to 4.2.10.