Windows CVE-2026-21251
HIGHCVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionNVD
Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation in Windows Cluster Client Failover exploits a use-after-free memory vulnerability, enabling authenticated local users to gain elevated system privileges. The flaw affects Windows Server 2016, 2019, and 2025 installations where an attacker with existing local access can trigger the vulnerability through the failover clustering component. …
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RemediationAI
Within 24 hours: Inventory all systems running Windows Cluster Client Failover and assess exposure; restrict cluster administrative access to essential personnel only. Within 7 days: Implement enhanced monitoring for unusual privilege escalation attempts and review cluster access logs for suspicious activity. …
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