8.4

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

CVSS: 8.4v3.1HighKEVRansomwareAnalyzed
Published 12-12-2018Last modified 21-10-2025
Open JSON

Vulnerability summary

CVE-2018-8639 is a high (CVSS 8.4) Improper Resource Shutdown or Release vulnerability in Microsoft Windows. It is known to be exploited: CISA lists it, first on 03-03-2025. It has been used in ransomware campaigns. EPSS estimates a 22.18% chance of exploitation in the next 30 days, higher than 97.6% of scored vulnerabilities.

Overall risk
90/100
0100
Critical · default modelHow is this calculated?
CVSS score
8.4/10
010
High · v3.1 (CVE.org)
EPSS score
22.18%
0%100%
High · 0.00 pp in 30 days
KEVListedCISA
RansomwareKnown useFlagged by CISA
Public exploits0No public exploits recorded

Timeline

  1. 12-12-2018
    PublishedVulnerability first disclosed.
  2. 03-03-2025
    Added to CISA KEVMicrosoft Windows Win32k Improper Resource Shutdown or Release Vulnerability
  3. 24-03-2025
    CISA remediation dueApply mitigations per vendor instructions.
  4. 21-10-2025
    Last modifiedVulnerability information updated.

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 metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

22.18%

Chance of exploitation in the next 30 days

Percentile

98%

Versus all other CVEs

30-day change

0.00 pp

From 22.18% on 19-09-2026

19-09-202619-10-2026
EPSS score
22.18%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
03-03-2025
Federal due date
24-03-2025
Ransomware

CISA required action

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

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Microsoft17 products
  • windows_1032-bit Systems | Version 1607 for 32-bit Systems | Version 1607 for x64-based Systems | Version 1703 for 32-bit Systems | Version 1703 for x64-based Systems | Version 1709 for 32-bit Systems | Version 1709 for ARM64-based Systems | Version 1709 for x64-based Systems | Version 1803 for 32-bit Systems | Version 1803 for ARM64-based Systems | Version 1803 for x64-based Systems | Version 1809 for 32-bit Systems | Version 1809 for ARM64-based Systems | Version 1809 for x64-based Systems | x64-based Systems
  • windows_10_1507na
  • windows_10_1607na
  • windows_10_1703na
  • windows_10_1709na

1 vendor · 17 products

References

3 links