Windows Hyper-V Elevation of Privilege Vulnerability

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

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9.3CVSS out of 10Critical severity

Scope

What the vendor says is affected

Windows Server 2022
Windows Server 2022 (Server Core installation)
Windows 11 Version 23H2 for ARM64-based Systems
Windows 11 Version 23H2 for x64-based Systems

Versions the vendor lists as fixed

10.0.20348.5139
10.0.20348.5074
10.0.22631.7079
10.0.22631.7219

Next step

What the vendor recommends

Install KB5087545. Install KB5087424. Install KB5087420. Install KB5093998.

Review the complete instructions on the vendor's site

Timeline

When this advisory changed

May 12, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Sep 27, 2026 at 11:11 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.

Vulnerabilities

CVEs named in this advisory

CVE-2026-40402View CVSS, KEV, EPSS, and threat context

Source

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Vendor: Microsoft Security Response Center
Advisory ID: CVE-2026-40402
Last source check: Sep 27, 2026 at 11:11 PM UTC

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Your environment

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What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

When this advisory changed

CVEs named in this advisory

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