MSRC-CVE-2026-33840 — Win32k Elevation of Privilege Vulnerability

Summary

Impact: Elevation of Privilege. Microsoft rating: Important. Not known to be exploited — Exploitation More Likely. Customer action: Required.

Details

What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

Security updates
10.0.26100.32860 — https://support.microsoft.com/help/5087539
10.0.26100.32772 — https://support.microsoft.com/help/5087423
10.0.26200.8457 — https://support.microsoft.com/help/5089549
10.0.26200.8390 — https://support.microsoft.com/help/5089466
10.0.28000.2113 — https://support.microsoft.com/help/5089548

Vulnerabilities 1

High 7.8

CVE-2026-33840

Win32k Elevation of Privilege Vulnerability

Use after free in Windows Win32K - ICOMP allows an authorized attacker to elevate privileges locally.

Microsoft Windows Server 2025 Windows Server 2025 (Server Core installation) Windows 11 Version 24H2 Windows

May 12, 2026

Revision history

2026-06-23 #3
Updated an acknowledgement. This is an informational change only.
2026-05-19 #2
Acknowledgement added. This is an informational change only.
2026-05-12 #1
Information published.

References

CVE-2026-33840 Win32k Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33840
Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
Common Vulnerability Scoring System
https://www.first.org/cvss