Microsoft Windows: information disclosure flaw under attack

What is affected

Microsoft Windows is found on ordinary personal computers and phones, so this is not only a problem for companies. If you use it and have not updated since the fix was released, you are exposed.

An information disclosure vulnerability exists in the way that the Windows SMB Server handles certain requests, which could lead to information disclosure from the server.

What an attacker can do

This is a information disclosure flaw. It lets an attacker read data they are not supposed to see, such as memory contents, credentials or internal files. It is often the first step of a larger attack.

How it is reached

Over the internet or network

Access the attacker needs

A basic user account

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. Update Microsoft Windows now. Open the update or "About" screen, install whatever is offered and restart the app or device, because the fix is not active until you do.
2. Turn on automatic updates so the next fix arrives without you having to look for it.
3. If your device is too old to receive this update, stop using the affected app for anything sensitive and plan a replacement.

Apply updates per vendor instructions.

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on May 23, 2022, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by June 13, 2022, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 9.6% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 95% of all scored vulnerabilities.

Its CVSS severity score is 6.5 out of 10 (medium), as recorded in the US National Vulnerability Database.

Technical description

An information disclosure vulnerability exists in the way that the Windows SMB Server handles certain requests, aka 'Windows SMB Information Disclosure Vulnerability'. This CVE ID is unique from CVE-2019-0704, CVE-2019-0821.