1. Home
  2. CVE Database
  3. CVE-2026-21251
HIGH · 7.8

CVE-2026-21251

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

Vulnerability Description

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

CVSS Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH

Affected Products

VendorProductVersions
MicrosoftWindows Server 2016< 10.0.14393.8868
MicrosoftWindows Server 2019< 10.0.17763.8389
MicrosoftWindows Server 2022< 10.0.20348.4711
MicrosoftWindows Server 2022 23H2< 10.0.25398.2149
MicrosoftWindows Server 2025< 10.0.26100.32313

Related Weaknesses (CWE)

CWE-416

References

FAQ

What is CVE-2026-21251?

CVE-2026-21251 is a vulnerability with a CVSS score of 7.8 (HIGH). Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.

How severe is CVE-2026-21251?

CVE-2026-21251 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-21251?

Check the references section above for vendor advisories and patch information. Affected products include: Microsoft Windows Server 2016, Microsoft Windows Server 2019, Microsoft Windows Server 2022, Microsoft Windows Server 2022 23H2, Microsoft Windows Server 2025.