How severe is CVE-2021-20328?

CVE-2021-20328 has a CVSS 3.x base score of 6.4, rated medium severity. It is exploitable over an adjacent network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-20328 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20328?

CVE-2021-20328 primarily affects Mongodb Java Driver. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20328?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-20328 published?

CVE-2021-20328 was published on 2021-02-25 and last updated on 2026-06-17.

CVE-2021-20328

CVE-2021-20328 is a medium-severity vulnerability in Mongodb Java Driver with a CVSS 3.x base score of 6.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: Medium (CVSS 3.x base score 6.4)
CVSS v2: 4.3
EPSS exploit prediction: 0% (35th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Mongodb Java Driver
Published: 2021-02-25
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-20328?: 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.
How severe is CVE-2021-20328?: CVE-2021-20328 has a CVSS 3.x base score of 6.4, rated medium severity. It is exploitable over an adjacent network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-20328 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20328?: CVE-2021-20328 primarily affects Mongodb Java Driver. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20328?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20328 published?: CVE-2021-20328 was published on 2021-02-25 and last updated on 2026-06-17.

References

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

Affected products (3)

cpe:2.3:a:mongodb:java_driver:*:*:*:*:*:mongodb:*:*
cpe:2.3:a:quarkus:quarkus:*:*:*:*:*:*:*:*
cpe:2.3:a:quarkus:quarkus:1.13.3:*:*:*:*:*:*:*

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