CVE-2018-8639 Microsoft Windows Win32k Improper Resource Shutdown or Release

Exploited in the wild High 8.4 Published 12 Dec 2018 Updated 21 Oct 2025

An attacker can exploit a Win32k memory handling flaw to gain elevated privileges on affected Windows systems.

Exploited in the wild: Since 3 Mar 2025
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2018-8639?

CVE-2018-8639 is a high-severity vulnerability in Microsoft Windows 10 1507, published on 12 Dec 2018. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka "Win32k Elevation of Privilege Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2019, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers. This CVE ID is unique from CVE-2018-8641.

Weakness: CWE-404

Which versions are affected by CVE-2018-8639?

It affects 13 products.

Products include Microsoft Windows 10 1507, Microsoft Windows 10 1607, Microsoft Windows 10 1703, Microsoft Windows 10 1709, Microsoft Windows 10 1803, Microsoft Windows 10 1809 and 7 more.

How do I fix CVE-2018-8639?

No fix has been published for CVE-2018-8639 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 24 Mar 2025.

Is CVE-2018-8639 being exploited?

Yes. Attackers have exploited CVE-2018-8639 in the wild since at least 3 Mar 2025, including in ransomware campaigns.

Public exploit code: 2 proofs of concept on GitHub.

All Microsoft Windows 10 1507 vulnerabilities

Sources

Also known as GHSA-93mm-g479-2cx4.