CVE-2021-32040: MongoDB

High severity, CVSS 7.5. EPSS: 2% chance of exploitation in the next 30 days.

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.

Affected products

• MongoDB MongoDB: from 4.2.0, before 4.2.16 (fixed in 4.2.16); from 4.4.0, before 4.4.11 (fixed in 4.4.11); from 5.0.0, before 5.0.4 (fixed in 5.0.4)

Published 2022-04-12. Last modified 2026-06-17.