Access Control Flaw in Windows Hyper-V by Microsoft
CVE-2026-21255

8.8HIGH

Key Information:

Vendor

Microsoft
Status
Windows 11 Version 26h1
Windows 11 Version 26h1
Windows 10 Version 1809
Windows Server 2019
Vendor
CVE Published:
10 February 2026

What is CVE-2026-21255?

An improper access control vulnerability in Windows Hyper-V allows authorized attackers to locally bypass security features, posing risks to the integrity of the virtualization environment. This issue may lead to unauthorized access to sensitive information and compromise system security.

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Affected Version(s)

Windows 10 Version 1607 x64-based Systems 10.0.14393.0 < 10.0.14393.8868

Windows 10 Version 1809 x64-based Systems 10.0.17763.0 < 10.0.17763.8389

Windows 10 Version 21H2 x64-based Systems 10.0.19044.0 < 10.0.19044.6937

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE...
vendor-advisorypatch

CVSS V3.1

Score:
8.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

JSON
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