CVE-2026-21255

Published: Feb 10, 2026Modified: Feb 11, 2026

8.8

Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploitability: 2.0 / Impact: 6.0

Source: secure@microsoft.com

Description

Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.

Affected (15)

Products: Microsoft: Windows 10 1607, Windows 10 1809, Windows 10 21h2, Windows 10 22h2, Windows 11 23h2, Windows 11 24h2, Windows 11 25h2, Windows Server 2016, Windows Server 2019, Windows Server 2022, Windows Server 2022 23h2, Windows Server 2025

12 products

Windows 10 1607

Windows 10 1809

Windows 10 21h2

Windows 10 22h2

Windows 11 23h2

Windows 11 24h2

Windows 11 25h2

Windows Server 2016

Windows Server 2019

Windows Server 2022

Windows Server 2022 23h2

Windows Server 2025

Configuration A

15 vulnerable

Vulnerable Software	Affected Versions
Microsoft Windows 10 1607	Before 10.0.14393.8868
Microsoft Windows 10 1809	Before 10.0.17763.8389
Microsoft Windows 10 21h2	Before 10.0.19044.6937
Microsoft Windows 10 22h2	Before 10.0.19045.6937
Microsoft Windows 11 23h2	Before 10.0.22631.6649
Microsoft Windows 11 23h2	Before 10.0.22631.6649
Microsoft Windows 11 24h2	Before 10.0.26100.7781
Microsoft Windows 11 24h2	Before 10.0.26100.7781
Microsoft Windows 11 25h2	Before 10.0.26200.7781
Microsoft Windows 11 25h2	Before 10.0.26200.7781
Microsoft Windows Server 2016	Before 10.0.14393.8868
Microsoft Windows Server 2019	Before 10.0.17763.8389
Microsoft Windows Server 2022	Before 10.0.20348.4711
Microsoft Windows Server 2022 23h2	Before 10.0.25398.2149
Microsoft Windows Server 2025	Before 10.0.26100.32313

Related CWEs

Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

References (1)

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21255

Source: secure@microsoft.com

Vendor Advisory

Timeline

No history available yet.