The MongoDB Entity Framework Core provider does not neutralize special elements in values passed to SetProperty when an…

The MongoDB Entity Framework Core provider does not neutralize special elements in values passed to SetProperty when an ExecuteUpdate call also contains a setter that reads the entity being updated. In that case the update is sent as an aggregation pipeline, and a caller-supplied string beginning with $ is evaluated as an expression rather than stored as data. A party who can influence such a value may modify or remove fields in the records being updated, or copy other fields of the same record into them.