CVE-2026-21251

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

7.8

Vector

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

Exploitability: 1.8 / Impact: 5.9

Source: secure@microsoft.com

Description

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

Affected (5)

Products: Microsoft: Windows Server 2016, Windows Server 2019, Windows Server 2022, Windows Server 2022 23h2, Windows Server 2025

5 products

Windows Server 2016

Windows Server 2019

Windows Server 2022

Windows Server 2022 23h2

Windows Server 2025

Configuration A

5 vulnerable

Vulnerable Software	Affected Versions
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

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

References (1)

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21251

Source: secure@microsoft.com

Vendor Advisory

Timeline

No history available yet.