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NVD / CVE Program· CNA mongodb

CVE-2021-20333: Server log entry spoofing via newline injection

MediumCVSS 5.3 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.3% (FIRST EPSS); higher than 70.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Sending specially crafted commands to a MongoDB Server may result in artificial log entries being generated or for log entries to be split. This issue affects MongoDB Server v3.6 versions prior to 3.6.20; MongoDB Server v4.0 versions prior to 4.0.21 and MongoDB Server v4.2 versions prior to 4.2.10.

Published
Jul 23, 2021
Updated
Jun 16, 2026
EPSS
1.3% · 70th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.3%

CNA vs NVD score

NVD
5.3
CNA · mongodb
5.3
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-20333

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mongodbmongodb

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mongodb). Independent of NVD's CPE analysis and usually ahead of it.

  • MongoDB Inc. MongoDB Server

    • 3.6 and later · before 3.6.20affected
    • 4.0 and later · before 4.0.21affected
    • 4.2 and later · before 4.2.10affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mongodb mongodb3.6.0 and later · before 3.6.20
  • mongodb mongodb4.0.0 and later · before 4.0.21
  • mongodb mongodb4.2.0 and later · before 4.2.10

Same product

mongodb: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-14847Zlib compressed protocol header length confusion may allow memory readKEV
    89Now
  • CVE-2013-1892MongoDB before 2.0.9 and 2.2.x before 2.2.4 does not properly validate requests to the nativeHelper function in SpiderMonkey, which allows…
    40Plan
  • CVE-2025-3085MongoDB Server running on Linux may allow unexpected connections where intermediate certificates are revoked
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2018-25004Mar 1, 2021 · Invariant failure when explaining a find with a UUID
    19Monitor
  • ← EarlierCVE-2021-20326Apr 30, 2021 · Specially crafted query may result in a denial of service of mongod
    26Monitor
  • Later →CVE-2021-32037Nov 24, 2021 · User may trigger invariant when allowed to send commands directly to shards
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-117 · Improper Output Neutralization for Logs

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

All records