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Fencer Intel
medium 6.5

CVE-2018-20802 json

Post-auth queries on compound index may crash mongod

published 2020-11-23 5 y ago modified 2026-06-17 4 mo ago also EUVD-2018-13344

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits
0
none known

Summary

A user authorized to perform database queries may trigger denial of service by issuing specially crafted queries with compound indexes affecting QueryPlanner. This issue affects MongoDB Server v3.6 versions prior to 3.6.9 and MongoDB Server v4.0 versions prior to 4.0.3.

Patch / fix

  • MongoDB Inc. MongoDB Server 3.6.9, 4.0.3
  • mongodb Ubuntu Pro 18.04 LTS 1:3.6.3-0ubuntu1.4+esm1

ubuntu advisories UBUNTU-CVE-2018-20802

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-20802 updated cvss 6.5

mongodb: Denial of service via crafted queries with compound indexes affecting QueryPlanner

  • Red Hat OpenStack Platform 10 (Newton) mongodb, mongodb-server
    affected: no fix planned “Out of support scope”
  • Red Hat Software Collections rh-mongodb36-mongodb, rh-mongodb36-mongodb-test, rh-mongodb36-mongodb-server, rh-mongodb36-mongodb-syspaths, rh-mongodb36-mongodb-server-syspaths
    affected: no fix planned “Will not fix”
  • Red Hat Advanced Cluster Management for Kubernetes 2 mongodb Red Hat Update Infrastructure 3 for Cloud Providers mongodb
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.58% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:N/A:P

Affected products

  • MongoDB Inc. MongoDB Server

Classification

Weakness
  • CWE-394 Unexpected Status Code or Return Value
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.