Critical severity · published May 12, 2026
CVE-2026-40402
Windows Hyper-V Elevation of Privilege Vulnerability
9.3
CVSS
0.3%
EPSS
No
On KEV
Description
Use after free in Windows Hyper-V allows an unauthorized attacker to elevate privileges locally.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 26% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
W1
Windows 11 version 23H2 · Microsoft
10.0.22631.0 before 10.0.22631.7079; 10.0.22631.0 before 10.0.22631.7219 · source: vendor
WS
Windows Server 2022 · Microsoft
10.0.20348.0 before 10.0.20348.5139 · source: vendor, NVD
W1
Windows 11 23h2 · Microsoft
before 10.0.22631.7079; before 10.0.22631.7079 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40402
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-40402
Vendor Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40402
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