CVE-2021-20328

MongoDB Java driver client-side field level encryption not verifying KMS host name

MEDIUM

6.8

CVSS Score

Published: February 25, 2021 at 04:30 PM UTC

Updated: June 17, 2026 at 03:33 AM UTC

2 products affected across 2 vendorsQuarkusJava Driver

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Severity

MEDIUM6.8

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

Description

Specific versions of the Java driver that support client-side field level encryption (CSFLE) fail to perform correct host name verification on the KMS server’s certificate. This vulnerability in combination with a privileged network position active MITM attack could result in interception of traffic between the Java driver and the KMS service rendering Field Level Encryption ineffective. This issue was discovered during internal testing and affects all versions of the Java driver that support CSFLE. The Java async, Scala, and reactive streams drivers are not impacted. This vulnerability does not impact driver traffic payloads with CSFLE-supported key services originating from applications residing inside the AWS, GCP, and Azure network fabrics due to compensating controls in these environments. This issue does not impact driver workloads that don’t use Field Level Encryption.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Java Driver · MongoDB

95%

3.11 ≤ v ≤ 3.11.23.11.0 ≤ v < 3.11.33.12 ≤ v ≤ 3.12.73.12.0 ≤ v < 3.12.84.0 ≤ v ≤ 4.0.54.0.0 ≤ v < 4.0.64.1 ≤ v ≤ 4.1.14.1.0 ≤ v < 4.1.24.2.0 ≤ v < 4.2.13.11 3.12 4.0 4.1 4.2.0

Affected range stops below 3.11.3, so it looks safe — our inference, not a vendor statement

Affected range stops below 3.12.8, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.0.6, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.1.2, so it looks safe — our inference, not a vendor statement

Affected range stops below 4.2.1, so it looks safe — our inference, not a vendor statement

Quarkus · Quarkus

95%

v < 1.13.31.13.3

Affected range stops below 1.13.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://jira.mongodb.org/browse/JAVA-4017

References (1)

x_refsource_MISCIssue TrackingPatchVendor Advisory

Source: [email protected]

https://jira.mongodb.org/browse/JAVA-4017

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.8MEDIUM[email protected]

Attack Vector: ADJACENT_NETWORK
Complexity: HIGH
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-295

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