CVE-2018-20803: Infinite loop in aggregation expression

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-11-23 · updated 2026-06-17
Weakness: CWE-835

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 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.

Affected products

MongoDB: from 3.4.0 before 3.4.19; from 3.6.0 before 3.6.10; from 4.0.0 before 4.0.5 — fixed in 3.4.19, 3.6.10, 4.0.5

How to fix

Upgrade to a fixed version: MongoDB 3.4.19, 3.6.10, 4.0.5. Check the vendor advisory for mitigations.

References

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