CVE-2021-20331: MongoDB C# Driver

Medium severity, CVSS 4.9. EPSS: 0.6% chance of exploitation in the next 30 days.

Specific versions of the MongoDB C# Driver may erroneously publish events containing authentication-related data to a command listener configured by an application. The published events may contain security-sensitive data when commands such as "saslStart", "saslContinue", "isMaster", "createUser", and "updateUser" are executed. Without due care, an application may inadvertently expose this authenticated-related information, e.g., by writing it to a log file. This issue only arises if an application enables the command listener feature (this is not enabled by default). This issue affects the MongoDB C# Driver v2.12 versions prior to and including 2.12.1.

Affected products

• MongoDB C# Driver: from 2.12.0, before 2.12.2 (fixed in 2.12.2); version 2.11.0 only

Published 2021-05-13. Last modified 2026-06-17.