CVE-2021-20328 — mongodb-driver
MEDIUMCVE-2021-20328 is a medium-severity (CVSS 6.8) CWE-295 vulnerability in org.mongodb:mongodb-driver. A fix is available for org.mongodb:mongodb-driver — see the affected versions and patch details below.
Improper Certificate Validation in MongoDB
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-20328.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2021-20328 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.mongodb:mongodb-driver☕org.mongodb:mongodb-driver☕org.mongodb:mongodb-driver-sync☕org.mongodb:mongodb-driver-sync☕org.mongodb:mongodb-driver-sync☕org.mongodb:mongo-java-driver☕org.mongodb:mongo-java-driver☕org.mongodb:mongodb-driver-legacy+6 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.mongodb:mongodb-driver | ≥ 3.11.0&&< 3.11.3 | 3.11.3org.mongodb:mongodb-driver:3.11.3 |
| ☕Maven | org.mongodb:mongodb-driver | ≥ 3.12.0&&< 3.12.8 | 3.12.8org.mongodb:mongodb-driver:3.12.8 |
| ☕Maven | org.mongodb:mongodb-driver-sync | ≥ 4.0.0&&< 4.0.6 | 4.0.6org.mongodb:mongodb-driver-sync:4.0.6 |
| ☕Maven | org.mongodb:mongodb-driver-sync | ≥ 4.1.0&&< 4.1.2 | 4.1.2org.mongodb:mongodb-driver-sync:4.1.2 |
| ☕Maven | org.mongodb:mongodb-driver-sync | ≥ 4.2.0&&< 4.2.1 | 4.2.1org.mongodb:mongodb-driver-sync:4.2.1 |
| ☕Maven | org.mongodb:mongo-java-driver | ≥ 3.11.0&&< 3.11.3 | 3.11.3org.mongodb:mongo-java-driver:3.11.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.mongodb:mongodb-driver, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.mongodb:mongodb-driver to 3.11.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-20328 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-20328 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-20328. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Integration | mongodb-driver | RHSA-2021:4918 |
| Red Hat Integration Camel Quarkus 2 | see advisory | RHSA-2021:4767 |
| Red Hat Integration Debezium 1.4.2 | mongodb-driver | RHSA-2021:0871 |
Frequently Asked Questions
Is CVE-2021-20328 in your dependencies?
O3 Security finds CVE-2021-20328 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.