CVE-2026-40369: Windows Kernel 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

EPSS Score

4.72% (percentile: 90.7%)

Description

Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges locally.

FAQ

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

Detection & Weaponization (1 sources)

Maturity: Exploit

• GitHub PoC: 5 repositories

Affected Products (8)

Windows

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

Security Updates (5)

• 5087539
• 5087423
• 5089549
• 5089466
• 5089548

Acknowledgments

<a href="https://www.linkedin.com/in/th&#233;o-d-75a617265/">Th&#233;o DUTEIS</a>, Calif.io in collaboration with Claude and Anthropic Research, <a href="https://doyensec.com/">Adrian Denkiewicz at Doyensec in collaboration with Anthropic Research</a>, <a href="https://sec-fault.com/">Len Sadowski (lytnc)</a> and <a href="https://ozbsec.com/">Oguz Bektas (_ozb_)</a>

Revision History

• 2026-05-12: Information published.