Windows SMBv3 Client/Server Information Disclosure Vulnerability

An information disclosure vulnerability exists in the way that the Microsoft Server Message Block 3.1.1 (SMBv3) protocol handles certain requests. An attacker who successfully exploited the vulnerability could obtain information to further compromise the user’s system.

To exploit the vulnerability against a server, an unauthenticated attacker could send a specially crafted packet to a targeted SMBv3 server. To exploit the vulnerability against a client, an unauthenticated attacker would need to configure a malicious SMBv3 server and convince a user to connect to it.

The security update addresses the vulnerability by correcting how the SMBv3 protocol handles these specially crafted requests.