Critical 9.3Published May 12, 2026

CVE-2026-40402Windows Hyper-V Elevation of Privilege Vulnerability

Updated under an hour ago (Oct 26, 2026, 5:00 PM ET)

Does this affect you?

It affects Microsoft Windows 11 version 23H2 and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for Microsoft Windows 11 version 23H2

Exploited in the last 30 days

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

CVSS: 9.3 CRITICAL (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
Weakness (CWE): CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: microsoft
NVD analysis: Analyzed
Record last updated: Aug 10, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Microsoft Windows 11 version 23H2 microsoft:windows_11_23h2	from 10.0.22631.0 before 10.0.22631.7079	CNA record
Microsoft Windows Server 2022 microsoft:windows_server_2022 (from the name)	from 10.0.20348.0 before 10.0.20348.5139	CNA record
microsoft windows_11_23h2 microsoft:windows_11_23h2	before 10.0.22631.7079; before 10.0.22631.7079	NVD
microsoft windows_server_2022 microsoft:windows_server_2022	before 10.0.20348.5074	NVD

References

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40402	vendor-advisory, patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.