SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityAnalyzed

CVE-2018-8639

Microsoft Windows Win32k Improper Resource Shutdown or Release Vulnerability

KEVHIGH 7.8EPSS 22.2%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 24 March 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

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.

CVSS 3.1
7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS
22.18% probability · 98th percentile
CISA KEV
Listed 3 March 2025 · due 24 March 2025 · used in ransomware campaigns
Weakness
CWE-404
Affected
microsoft/windows 10 1507 · microsoft/windows 10 1607 · microsoft/windows 10 1703 · microsoft/windows 10 1709 · microsoft/windows 10 1803 · microsoft/windows 10 1809 · microsoft/windows 7 · microsoft/windows 8.1 · microsoft/windows rt 8.1 · microsoft/windows server 2008 · microsoft/windows server 2012 · microsoft/windows server 2016 · microsoft/windows server 2019
Source
secure@microsoft.com

CISA notes

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2018-8639 ; https://nvd.nist.gov/vuln/detail/CVE-2018-8639

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.