CVE-2021-20333Network attack vector

Server log entry spoofing via newline injection

Published Jul 23, 2021 · Updated Sep 17, 2024

Improper output neutralization for logs in MongoDB Server 3.6 before 3.6.20 allows remote attackers to spoof entries via crafted commands. The command logging path accepts newline characters from specially crafted commands, splitting records and creating artificial log entries. No authentication is required, so reachable servers can have their security logs falsified; the record reports log integrity impact without data disclosure or service interruption.

CVSS severity5.3
Medium
EPSS probability1.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper output neutralization for logs in MongoDB Server 3.6 before 3.6.20 allows remote attackers to spoof entries via crafted commands. The command logging path accepts newline characters from specially crafted commands, splitting records and creating artificial log entries. No authentication is required, so reachable servers can have their security logs falsified; the record reports log integrity impact without data disclosure or service interruption.

The record

CVE
CVE-2021-20333
Published
Jul 23, 2021
Updated
Sep 17, 2024
Vendor
MongoDB
Product
MongoDB Server
Classifications
CWE-117, CWE-116
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=3.6 <3.6.20
  2. Affected versionversion=4.0 <4.0.21
  3. Affected versionversion=4.2 <4.2.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MongoDB · MongoDB Serverversion=3.6 <3.6.20; version=4.0 <4.0.21; version=4.2 <4.2.10

Published CVSS scores

5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-117Improper Output Neutralization for Logs
CWE-116Improper Encoding or Escaping of Output

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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