Use After Free in Microsoft Windows 11 23h2
CVE-2026-40402
Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (28.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 28.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.000
Affected products
- Microsoft Windows 11 23h2
- Microsoft Windows 11 Version 22h3 — versions 10.0.22631.0
- Microsoft Windows 11 Version 23h2 — versions 10.0.22631.0
- Microsoft Windows Server 2022 — versions 10.0.20348.0
- Microsoft Windows Server 2022
Weakness classification (CWE)
References
- Windows Hyper-V Elevation of Privilege Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-40402?
- CVE-2026-40402 is a critical-severity vulnerability in Microsoft Windows 11 23h2, classified under Use After Free. CVSS score: 9.3/10. Published 2026-05-12.
- How severe is CVE-2026-40402?
- Critical severity. CVSS v3 base score is 9.3 out of 10.