Privilege Escalation Vulnerability in Microsoft Windows Cluster Client Failover
CVE-2026-21251

7.8HIGH

Key Information:

Vendor

Microsoft
Status
Windows Server 2016
Windows Server 2016 (server Core Installation)
Windows Server 2019
Windows Server 2019 (server Core Installation)
Vendor
CVE Published:
10 February 2026

What is CVE-2026-21251?

A vulnerability in Windows Cluster Client Failover could allow an authorized attacker to exploit a use after free scenario, potentially granting them the ability to elevate their privileges locally. This issue, if exploited, can compromise system integrity and security, highlighting the need for prompt patching and addressing cybersecurity hygiene.

Affected Version(s)

Windows Server 2016 (Server Core installation) x64-based Systems 10.0.14393.0 < 10.0.14393.8868

Windows Server 2016 x64-based Systems 10.0.14393.0 < 10.0.14393.8868

Windows Server 2019 (Server Core installation) x64-based Systems 10.0.17763.0 < 10.0.17763.8389

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE...
vendor-advisorypatch

CVSS V3.1

Score:
7.8
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.