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CVE-2025-29955: Windows Hyper-V Denial of Service Vulnerability

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-05-13 · updated 2026-06-17
• Weakness: CWE-20

Description

Improper input validation in Windows Hyper-V allows an unauthorized attacker to deny service locally.

Affected products

• Microsoft Windows 11: before 10.0.26100.4061 — fixed in 10.0.26100.4061
• Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.1611 — fixed in 10.0.25398.1611
• Microsoft Windows Server 2025: before 10.0.26100.4061 — fixed in 10.0.26100.4061
• Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.4061 — fixed in 10.0.26100.4061
• Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): from 10.0.25398.0 before 10.0.25398.1611 — fixed in 10.0.25398.1611
• Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.4061 — fixed in 10.0.26100.4061

How to fix

Upgrade to a fixed version: Microsoft Windows 11 10.0.26100.4061; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1611; Microsoft Windows Server 2025 10.0.26100.4061; Microsoft Windows 11 10.0.26100.4061; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1611; Microsoft Windows Server 2025 10.0.26100.4061. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-29955

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