CVE-2019-0859 Microsoft Win32k Privilege Escalation Vulnerability
Microsoft Win32k fails to properly handle objects in memory causing privilege escalation. Successful exploitation allows an attacker to run code in kernel mode.
From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.
Should You Worry?
- CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 3 Nov 2021.
- CISA lists it as known to be used in ransomware campaigns.
- Rated High severity (CVSS 7.8, scored by CISA).
- It has been in the catalogue for 1,829 days. Systems still unpatched now have almost certainly been scanned for it.
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 CVE ID is unique from CVE-2019-0685, CVE-2019-0803.
Affected Versions
| Product | Versions |
|---|---|
| Microsoft Windows | 7 for 32-bit Systems Service Pack 1 7 for x64-based Systems Service Pack 1 8.1 for 32-bit systems 8.1 for x64-based systems RT 8.1 10 for 32-bit Systems |
| Microsoft Windows Server | 2008 R2 for x64-based Systems Service Pack 1 (Core installation) 2008 R2 for Itanium-Based Systems Service Pack 1 2008 R2 for x64-based Systems Service Pack 1 2008 for 32-bit Systems Service Pack 2 (Core installation) 2012 2012 (Core installation) |
From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.
What To Do Now
- 1
Find it
Search your asset inventory and external attack surface for Microsoft Win32k. Include cloud images, appliances and anything a supplier runs for you.
Attack Surface Management - 2
- 3
Hunt for compromise
If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.
Incident Response - 4
Prove it is fixed
Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.
Penetration Testing
Vendor Advisories
The Compliance Clock
General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.
Not Sure If You Are Exposed?
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