.NET Framework Information Disclosure Vulnerability

An information disclosure vulnerability exists in Microsoft .NET 4.6.2 Framework’s Data Provider for SQL Server that could allow an attacker to access information that should be defended by the Always Encrypted feature. The vulnerability is caused when .NET Framework improperly uses a developer-supplied key. When this key is misused, it is also possible for access to data to be temporarily lost.

To exploit the vulnerability, an attacker who can access the incorrectly encrypted data could attempt to decrypt the data using an easily guessable key.

The security update addresses the vulnerability by correcting the way .NET Framework handles the developer-supplied key, and thus properly defends the data.