CVE-2018-8639
HIGHCISA KEVEPSS 97th pctlDescription
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.
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
Impact
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 97% of all known CVEs.
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
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 | 24% | - | - |
| CVE-2023-3206 | Medium | 5.3 | 19% | - | - |
| CVE-2018-8450 | High | 8.8 | 16% | - | - |
| CVE-2025-1103 | Medium | 6.5 | 13% | - | - |
Common questions
How do I fix 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.
Is CVE-2018-8639 being actively exploited?
Yes. CVE-2018-8639 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. CISA has also linked it to known ransomware campaigns. US federal agencies were required to remediate it by 2025-03-24. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2018-8639?
CVE-2018-8639 has a CVSS v3 base score of 7.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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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.