Assume that you use the TransactionScope class in Microsoft SQL Server 2014 client-side source code, and you do not explicitly open the SQL Server connection in a transaction. When the SQL Server connection is released, the transaction isolation level is reset incorrectly.
The issue was fixed in the following cumulative updates for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. We recommend that you download and install the latest cumulative updates for SQL Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.