High severity7.8NVD Advisory· Published Feb 10, 2026· Updated Jun 17, 2026

CVE-2026-21251

Description

Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.

Microsoft/Windows Server 20162 versions
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*range: <10.0.14393.8868
- (no CPE)range: 10.0.14393.0
Microsoft/Windows Server 20192 versions
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*range: <10.0.17763.8389
- (no CPE)range: 10.0.17763.0
Microsoft/Windows Server 20032 versions
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*range: <10.0.20348.4711
- (no CPE)range: 10.0.20348.0
Microsoft/Windows Server 2012
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
Range: <10.0.25398.2149
Microsoft/Windows Server 20252 versions
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*+ 1 more
- cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*range: <10.0.26100.32313
- (no CPE)range: 10.0.26100.0
Microsoft/Windows Failover Clusterllm-fuzzy
Microsoft/Windows Server 2016 (Server Core installation)v5
Range: 10.0.14393.0
Microsoft/Windows Server 2019 (Server Core installation)v5
Range: 10.0.17763.0
Microsoft/Windows Server 2022, 23H2 Edition (Server Core installation)v5
Range: 10.0.25398.0
Microsoft/Windows Server 2025 (Server Core installation)v5
Range: 10.0.26100.0