Use After Free in Microsoft Windows Server 2016
CVE-2026-21251
Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.
Vulnerability class: Use-After-Free
EPSS: 0.004 (33.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Microsoft Windows Server 2016 — versions 10.0.14393.0
- Microsoft Windows_server_2016
- Microsoft Windows Server 2016 (Server Core Installation) — versions 10.0.14393.0
- Microsoft Windows Server 2019 — versions 10.0.17763.0
- Microsoft Windows_server_2019
- Microsoft Windows Server 2019 (Server Core Installation) — versions 10.0.17763.0
- Microsoft Windows Server 2022 — versions 10.0.20348.0
- Microsoft Windows_server_2022
- Microsoft Windows_server_2022_23h2
- Microsoft Windows Server 2022, 23h2 Edition (Server Core Installation) — versions 10.0.25398.0
Weakness classification (CWE)
References
- secure@microsoft.com (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-21251?
- CVE-2026-21251 is a high-severity vulnerability in Microsoft Windows Server 2016, classified under Use After Free. CVSS score: 7.8/10. Published 2026-02-10.
- How severe is CVE-2026-21251?
- High severity. CVSS v3 base score is 7.8 out of 10.