Is CVE-2018-8639 in the CISA KEV catalog?

Yes. CVE-2018-8639 is on the CISA Known Exploited Vulnerabilities list, added 2025-03-03, and has known ransomware campaign use.

What is the CVSS severity of CVE-2018-8639?

CVE-2018-8639 has a CVSS v3 base score of 7.8 (HIGH).

What is the EPSS score for CVE-2018-8639?

CVE-2018-8639 has an EPSS score of 22.35% (97th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2018-8639?

No published fix for CVE-2018-8639 has been found yet. It is on the CISA Known Exploited Vulnerabilities list; federal agencies must remediate by 2025-03-24. Apply the vendor's mitigations per CISA's guidance.

CVE & CISA-KEV Catalog

CVE-2018-8639

HIGHCISA KEVEPSS 97th pctl

7.8

CVSS v3

NVD

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.

CWE-404

How to fix

Actively exploited, no published fix found yet

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.

Federal remediation due: 2025-03-24

Known ransomware campaign use

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

22.35%probability of exploitation in 30 days

97thpercentile

Very high risk: more likely to be exploited than 97% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Microsoft Windows Win32k Improper Resource Shutdown or Release Vulnerability

Microsoft Windows Win32k contains an improper resource shutdown or release vulnerability that allows for local, authenticated privilege escalation. An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode.

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

Remediation due: 2025-03-24

Associated with ransomware campaigns

References

Patch1

portal.msrc.microsoft.com

Third-Party Advisory1

securityfocus.com

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-404 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2022-44267	Medium	6.5	77%	-	Fix
CVE-2018-8120	High	7.0	74%	KEV + Ransom	-
CVE-2018-8210	High	7.8	25%	-	-
CVE-2023-3206	Medium	5.3	19%	-	-
CVE-2018-8450	High	8.8	16%	-	-
CVE-2025-1103	Medium	6.5	13%	-	-

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-29.