CVE-2021-20326Network attack vector

Authenticated service crash via crafted find query

Published Apr 30, 2021 · Updated Nov 19, 2024

Improper input validation in MongoDB Server 4.4 before 4.4.4 allows remote authenticated users to crash mongod with a crafted find query. The Querying component reaches an invariant failure, but MongoDB has not published the exact query or the specific validation operation that fails. Authorization to run the relevant find query is required, and successful exploitation interrupts database availability without reported data disclosure or modification.

CVSS severity6.5
Medium
EPSS probability0.95%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in MongoDB Server 4.4 before 4.4.4 allows remote authenticated users to crash mongod with a crafted find query. The Querying component reaches an invariant failure, but MongoDB has not published the exact query or the specific validation operation that fails. Authorization to run the relevant find query is required, and successful exploitation interrupts database availability without reported data disclosure or modification.

The record

CVE
CVE-2021-20326
Published
Apr 30, 2021
Updated
Nov 19, 2024
Vendor
MongoDB
Product
MongoDB Server
Classifications
CWE-20, CWE-732, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 30, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 19, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.4 <4.4.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

MongoDB · MongoDB Serverversion=4.4 <4.4.4

Published CVSS scores

4.0NISTAV:N/AC:L/Au:S/C:N/I:N/A:P
6.5MongoDB, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-732Incorrect Permission Assignment for Critical Resource
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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