Microsoft Windows: memory corruption 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.

Microsoft Windows Win32 Kernel Subsystem contains a use-after-free vulnerability that allows an authorized attacker to elevate privileges locally.

What an attacker can do

This is a memory corruption flaw. It lets an attacker corrupt the program's memory by feeding it specially crafted content: a web page, a file or a network message. The result ranges from a crash to the attacker running their own code.

How it is reached

Needs access to the device or a file opened on it

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 mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• msrc.microsoft.commsrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-24983

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on March 11, 2025, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by April 1, 2025, 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 1.4% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 71% of all scored vulnerabilities.

Its CVSS severity score is 7.0 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

Use after free in Windows Win32 Kernel Subsystem allows an authorized attacker to elevate privileges locally.