C# Driver

A data-validation flaw exists in the BSON handling and binary serialization path of the MongoDB C# Driver. When an application constructs a raw or lazy BSON document object from externally supplied binary data, the driver does not verify that the size quantity declared inside that data matches the amount of data actually provided, and it copies the data onto the wire unchanged. An unauthenticated party who can supply binary content to such an application can thereby cause additional elements to be inserted into, or existing elements to be removed from, the database command the application issues, without needing any database credentials of their own. This can result in unauthorized modification of stored data and disclosure of data outside the intended scope of the application's request, bounded by the database privileges the application itself holds.

Published: 2026-10-22T19:13:50.935Z
Updated: 2026-11-02T14:37:54.708Z

A data-query-logic neutralization weakness in the update-statement construction component of the MongoDB C# Driver can cause application-supplied values to be interpreted as query/update logic rather than as literal data. An application user who can influence the content of values that the application passes into the affected builder surface, without any special privilege beyond ordinary read-write application access, may cause stored data to be modified or removed in ways the application never intended. The result is unauthorized integrity impact on the affected application data; there is no direct loss of confidentiality or availability of the database service.

Published: 2026-10-22T19:13:57.376Z
Updated: 2026-10-30T19:26:33.459Z

A client-side encryption schema construction component in the MongoDB C# Driver places caller-supplied field identifiers into a position that is interpreted as a pattern expression, without normalizing or validating them. As a result, an application that designates certain fields for client-side field-level encryption may have the protection silently fail to apply, so data intended to be encrypted is stored and returned in cleartext; conversely, the rule may apply more broadly than intended. No user action is required to cause the condition, and any party with ordinary read access to the stored data — without possession of the encryption keys — can observe the unprotected values.

Published: 2026-10-22T19:13:58.414Z
Updated: 2026-10-30T19:27:22.054Z

The MongoDB C# Driver writes GeoJSON extra members without checking whether their names collide with reserved GeoJSON members such as type and coordinates. An application that places user-supplied field names into these extra members can store documents with duplicate geometry fields, so the server and the driver resolve different values for the same record. Affected records can also become unreadable through the driver, interrupting application code that reads them.

Published: 2026-10-22T19:13:47.839Z
Updated: 2026-11-02T14:30:35.153Z

The MongoDB C# Driver does not reject replacement documents whose top-level field names begin with a dollar sign in FindOneAndReplace, unlike other replace operations. An application that builds such a document from user-supplied field names can have the server apply update operators instead of a full replacement. The effect is limited to the document matched by the application's own filter, whose contents can be modified in ways the application did not intend.

Published: 2026-10-22T19:13:51.972Z
Updated: 2026-11-02T12:19:43.566Z