CVE-2026-81530: KMS master key exposure via unredacted credential serialization in driver settings string

Severity: medium (CVSS 5.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-27 · updated 2026-09-29
Weakness: CWE-532

Description

A weakness in the client-side encryption configuration surface of the MongoDB C# Driver causes sensitive key-management credential material supplied by the application to be reproduced verbatim in the driver's human-readable diagnostic representation of its client settings, instead of being masked as other secret fields are. A party able to read the application's logs, diagnostic output, or a process memory dump may thereby recover the plaintext credentials and use them to decrypt protected field data.

Affected products

MongoDB Inc MongoDB .NET/C# Driver: from 2.10.0 before 3.11.1 — fixed in 3.11.1

How to fix

Upgrade to a fixed version: MongoDB Inc MongoDB .NET/C# Driver 3.11.1. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-81530 or the next vulnerability affects your stack