What is CVE-2021-20327?

CVE-2021-20327 is a medium-severity security vulnerability in mongodb-client-encryption (npm), affecting versions = 1.2.0. It is fixed in 1.2.1.

How severe is CVE-2021-20327?

CVE-2021-20327 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of mongodb-client-encryption are affected by CVE-2021-20327?

mongodb-client-encryption (npm) versions = 1.2.0 is affected.

Is there a fix for CVE-2021-20327?

Yes. CVE-2021-20327 is fixed in 1.2.1. Upgrade to this version or later.

Is CVE-2021-20327 exploitable, and should I be worried?

Whether CVE-2021-20327 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2021-20327 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

CVE-2021-20327 in mongodb-client-encryption

Q: How do I fix CVE-2021-20327?

Upgrade mongodb-client-encryption to 1.2.1 or later.

Summary

mongodb-client-encryption vulnerable to Improper Certificate Validation

A specific version of the Node.js mongodb-client-encryption module does not perform correct validation of 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 Node.js driver and the KMS service rendering client-side field level encryption (CSFLE) ineffective. This issue was discovered during internal testing and affects mongodb-client-encryption module version 1.2.0, which was available from 2021-Jan-29 and deprecated in the NPM Registry on 2021-Feb-04. This vulnerability does not impact driver traffic payloads with CSFLE-supported key services from applications residing inside the AWS, GCP, and Azure nework fabrics due to compensating controls in these environments. This issue does not impact driver workloads that don’t use Field Level Encryption. This issue affect MongoDB Node.js Driver mongodb-client-encryption module version 1.2.0

Impact

CVE-2021-20327 has a CVSS score of 6.8 (Medium). The vector is reachable from an adjacent network, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.2.1); upgrading removes the vulnerable code path.

Affected versions

mongodb-client-encryption (= 1.2.0)

Security releases

mongodb-client-encryption → 1.2.1 (npm)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

Already deployed Kodem?

See it in your environment New to Kodem? Get a demo →

Remediation advice

Upgrade mongodb-client-encryption to 1.2.1 or later to resolve this vulnerability.

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2021-20327? CVE-2021-20327 is a medium-severity security vulnerability in mongodb-client-encryption (npm), affecting versions = 1.2.0. It is fixed in 1.2.1.
How severe is CVE-2021-20327? CVE-2021-20327 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of mongodb-client-encryption are affected by CVE-2021-20327? mongodb-client-encryption (npm) versions = 1.2.0 is affected.
Is there a fix for CVE-2021-20327? Yes. CVE-2021-20327 is fixed in 1.2.1. Upgrade to this version or later.
Is CVE-2021-20327 exploitable, and should I be worried? Whether CVE-2021-20327 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2021-20327 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2021-20327? Upgrade mongodb-client-encryption to 1.2.1 or later.