Title: Infinite loop in aggregation expression

Description:
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 Inc. MongoDB Server v4.0 versions prior to 4.0.5; v3.6 versions prior to 3.6.10; v3.4 versions prior to 3.4.19.

CVSS score:
This issue's CVSS:3.1 severity is scored at 6.5 using the following scoring metrics:
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected versions:
MongoDB Inc. MongoDB Server v4.0 versions prior to 4.0.5; v3.6 versions prior to 3.6.10; v3.4 versions prior to 3.4.19.

CWE: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')