CVE-2026-21255: Windows Hyper-V Security Feature Bypass Vulnerability
Improper access control in Windows Hyper-V allows an authorized attacker to bypass a security feature locally.
Other sources
Windows Hyper-V Security Feature Bypass Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.32370Fixed in 10.0.26100.32313Patch KB5075942 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.14393.8868Patch KB5075999 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.7840Fixed in 10.0.26100.7781Patch KB5077212 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.22631.6649Patch KB5075941 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26200.7840Fixed in 10.0.26200.7781Patch KB5077212 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.25398.2149Patch KB5075897 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.20348.4773Fixed in 10.0.20348.4711Patch KB5075943 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.19045.6937Patch KB5075912 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.17763.8389Patch KB5075904 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.28000.1575Patch KB5077179 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.19044.6937Patch KB5075912
Event History
Frequently Asked Questions
What is the severity of CVE-2026-21255?
CVE-2026-21255 has a high severity rating due to improper access control in Windows Hyper-V allowing attackers to bypass security features.
How do I fix CVE-2026-21255?
To fix CVE-2026-21255, apply the latest security patches provided by Microsoft for affected Windows products.
Which Windows versions are affected by CVE-2026-21255?
CVE-2026-21255 affects various Windows versions including Windows Server 2025, Windows 11, Windows 10, and Windows Server 2016.
Can CVE-2026-21255 be exploited remotely?
No, CVE-2026-21255 requires local access for exploitation, making it a local security feature bypass vulnerability.
Is there any workarounds available for CVE-2026-21255?
Currently, the recommended method to mitigate CVE-2026-21255 is to apply the specified security updates as there are no known workarounds.