CVE-2021-20327

Field-level encryption bypass via disabled certificate validation

Published Feb 25, 2021 · Updated Sep 16, 2024

Improper certificate validation in MongoDB mongodb-client-encryption 1.2.0 allows man-in-the-middle attackers to intercept KMS traffic. The kmsRequest method in bindings/node/lib/stateMachine.js sets rejectUnauthorized to false, so Node.js accepts an untrusted KMS TLS certificate. Exploitation requires a privileged network position and a workload using client-side field-level encryption outside the compensating controls of AWS, GCP, or Azure network fabrics.

CVSS severity6.8
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in MongoDB mongodb-client-encryption 1.2.0 allows man-in-the-middle attackers to intercept KMS traffic. The kmsRequest method in bindings/node/lib/stateMachine.js sets rejectUnauthorized to false, so Node.js accepts an untrusted KMS TLS certificate. Exploitation requires a privileged network position and a workload using client-side field-level encryption outside the compensating controls of AWS, GCP, or Azure network fabrics.

The record

CVE
CVE-2021-20327
Published
Feb 25, 2021
Updated
Sep 16, 2024
Vendor
MongoDB
Product
mongodb-client-encryption
Classifications
CWE-295, T1557
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=1.2.0

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

MongoDB · mongodb-client-encryptionversion=1.2.0

Published CVSS scores

6.8GitHub Security AdvisoryCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/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.

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No observations available

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

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

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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