FalehSec Exploited-vulnerability triage · joined from CISA KEV, NVD CVSS and EPSS

CVE-2018-8639

Microsoft · Windows · Microsoft Windows Win32k Improper Resource Shutdown or Release Vulnerability

Verdict
Patch soon · actively exploited, not reachable unauthenticated from the internet, and in the top 5% of CVEs by near-term exploitation probability

Added to CISA KEV 2025-03-03 · exploited in the wild for 573 days · used in ransomware campaigns

What an attacker can reach How likely Time What CISA says to do Sources All 545

What an attacker can reach

CVSS 7.8 HIGH. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.

Attack vectorlocalrequires local access to the machine
Privileges requiredlowneeds some credentials, so a fully anonymous attacker cannot reach it directly
User interactionnonecan be triggered with nobody interacting with the page or request
Base vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
WeaknessCWE-404

This describes the vulnerability. It says nothing about whether your systems run it.

How likely

EPSS puts the probability of exploitation in the next 30 days at 0.2218, which places it in the top 5% of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.

EPSS probability0.2218
Percentile0.976 — top 5%

Time

Added to KEV2025-03-03
Days exploited573
Federal remediation duenot set
Ransomware useknown to be used in ransomware campaigns

What CISA says to do

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

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.

Sources