CVE-2026-33840: Win32k Elevation of Privilege Vulnerability

Overview

Severity
High (CVSS 7.8)
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Elevation of Privilege
Exploit Status
Not Exploited
Exploitation Likelihood
More Likely
Patch Tuesday
2026-May
Released
2026-05-12
Last Updated
2026-06-23
EPSS Score
2.01% (percentile: 78.4%)

Description

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

FAQ

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

Affected Products (8)

Windows

  • Windows Server 2025 (Server Core installation)
  • Windows 11 Version 25H2 for ARM64-based Systems
  • Windows 11 Version 25H2 for x64-based Systems
  • Windows 11 Version 24H2 for ARM64-based Systems
  • Windows 11 Version 24H2 for x64-based Systems
  • Windows Server 2025
  • Windows 11 version 26H1 for x64-based Systems
  • Windows 11 Version 26H1 for ARM64-based Systems

Security Updates (5)

Acknowledgments

<a href="https://www.linkedin.com/in/boolgombear/">Minjea Park</a>, <a href="https://www.linkedin.com/in/boolgombear/">ji9umi</a> and <a href="https://www.linkedin.com/in/boolgombear/">Jmini</a> with <a href="https://stealien.com/id/main">Stealien</a>, Kentaro Kawane with GMO Cybersecurity by Ierae, Inc., <a href="https://www.linkedin.com/in/boolgombear/">Minjea Park</a> with <a href="https://stealien.com/">Stealien</a>,  Minjea Park, ji9umi and Jmini with Stealien, <a href="https://linkedin.com/in/jongseongkim">Jongseong Kim (nevul37) with UIUC</a>, <a href="https://linkedin.com/in/hwiwonlee">Hwiwon Lee (hwiwonl) with UIUC</a>, <a href="https://linkedin.com/in/kdj-smlijun">DongJun Kim (smlijun) with UIUC</a>, Younggi Park (grill66) with UIUC

Revision History

  • 2026-05-12: Information published.
  • 2026-05-19: Acknowledgement added. This is an informational change only.
  • 2026-06-23: Updated an acknowledgement. This is an informational change only.