CVE-2026-81528
MediumCVSS 5.4Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
A MongoDB C# driver document-replacement code path omits the element-name/shape validation that equivalent write paths apply, so a value supplied as a replacement is forwarded to the server without neutralization of query-language special elements.
Risk Assessment
An application passing untrusted, loosely-typed input as a replacement value may allow the database to interpret it as update logic, executing under the application's credentials and potentially modifying data unintentionally.
Recommendation
Upgrade the MongoDB C# Driver to a patched version that applies proper validation. Ensure that replacement values are strongly typed and sanitized before use.
Original NVD description (English source)
A MongoDB C# driver document-replacement code path omits the element-name/shape validation that the equivalent write paths apply, so a value supplied as a replacement is forwarded to the server without neutralization of query-language special elements. An application that passes untrusted, loosely-typed input as a replacement value therefore allows that input to be interpreted by the database as update logic rather than as data, executing under the application's own database credentials. Applications using strongly-typed document mappings are not affected.