CVE-2026-88099: Windows Failover Cluster Denial of Service Vulnerability
Uncaught exception in Windows Failover Cluster allows an unauthorized attacker to deny service over a network.
Other sources
Windows Failover Cluster Denial of Service Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33650Patch KB5126646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.20348.5761Patch KB5126655 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.17763.9376Patch KB5126651
Event History
Frequently Asked Questions
Which systems should be prioritized for review?
Review Microsoft Windows Server 2019, Windows Server 2022, and Windows Server 2025 systems that use Windows Failover Cluster functionality. The impact described is denial of service, with no confidentiality or integrity impact indicated.
Does exploitation require credentials or user interaction?
No. The vulnerability is described as exploitable by an unauthorized attacker over the network, with no privileges or user interaction required. Exploitation has high attack complexity.
What is the expected impact if exploitation succeeds?
An attacker could deny service. The provided severity vector indicates an availability impact only, with no stated confidentiality or integrity impact.