Security Digest · Vulnerability record · Known exploited
CVE-2018-8639: Microsoft Windows Win32k Improper Resource Shutdown or Release Vulnerability
Exploited in the wild (CISA KEV). 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…
CISA KEV · added 2025-03-03 CVSS 8.4 High EPSS 22.2% · p98
Should you act?
Exploited: patch now if you run it
CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Yes, if you run Microsoft Windows. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-03-03, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-03-24; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns.
- EPSS 22.2%, percentile 98: FIRST’s model estimates a 22.2% chance of exploitation activity in the next 30 days, higher than 98% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.
What it is
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.
CISA’s summary
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.
Weakness type: CWE-404.
Product: Microsoft Windows · Assigned by: microsoft · Published: 2018-12-12
Affected and fixed versions
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| Microsoft | Windows 7 | 32-bit Systems Service Pack 1, x64-based Systems Service Pack 1 |
| Microsoft | Windows Server 2012 R2 | (Server Core installation) |
| Microsoft | Windows RT 8.1 | Windows RT 8.1 |
| Microsoft | Windows Server 2008 | 32-bit Systems Service Pack 2, 32-bit Systems Service Pack 2 (Server Core installation), Itanium-Based Systems Service Pack 2, x64-based Systems Service Pack 2, x64-based Systems Service Pack 2 (Server Core installation) |
| Microsoft | Windows Server 2019 | (Server Core installation) |
| Microsoft | Windows Server 2012 | (Server Core installation) |
| Microsoft | Windows 8.1 | 32-bit systems, x64-based systems |
| Microsoft | Windows Server 2016 | (Server Core installation) |
| Microsoft | Windows Server 2008 R2 | Itanium-Based Systems Service Pack 1, x64-based Systems Service Pack 1, x64-based Systems Service Pack 1 (Server Core installation) |
| Microsoft | Windows 10 | 32-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… |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADP | 3.1 | 8.4 High | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- Attack vector: local access needed
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: added 2025-03-03; federal due date 2025-03-24. Known ransomware use: Known.
- 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.
- CISA SSVC assessment: exploitation active, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 22.18% probability of exploitation activity in the next 30 days; percentile 98.
Timeline
- — CVE record published by microsoft
- — Added to CISA’s Known Exploited Vulnerabilities catalog
- — CISA remediation deadline for US federal agencies
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- Listed in CISA KEV notes (msrc.microsoft.com) msrc.microsoft.com
Vulnerability records
- CVE.org record CVE-2018-8639 cve.org
- NVD entry CVE-2018-8639 nvd.nist.gov
Government
Other references from the CVE record and advisory
- 106093 securityfocus.com
- portal.msrc.microsoft.com portal.msrc.microsoft.com
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