CVE-2026-40402: Microsoft Windows 11 23h2

Critical severity, CVSS 9.3. EPSS: 0.4% chance of exploitation in the next 30 days.

Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.

Affected products

• Microsoft Windows 11 23h2: before 10.0.22631.7079 (fixed in 10.0.22631.7079)
• Microsoft Windows Server 2022: before 10.0.20348.5074 (fixed in 10.0.20348.5074)

Published 2026-05-12. Last modified 2026-06-17.