CVE-2026-88099 Windows Failover Cluster Denial of Service Vulnerability
An uncaught exception in Windows Failover Cluster allows unauthorized attackers to cause a denial of service over the network.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-88099?
CVE-2026-88099 is a medium-severity denial of service vulnerability in Microsoft Windows Server 2019, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Uncaught exception in Windows Failover Cluster allows an unauthorized attacker to deny service over a network.
Weakness: CWE-248
Which versions are affected by CVE-2026-88099?
It affects 3 products.
Products include Microsoft Windows Server 2019, Microsoft Windows Server 2022, Microsoft Windows Server 2025.
How do I fix CVE-2026-88099?
No fix has been published for CVE-2026-88099 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-88099 being exploited?
There is no known exploitation of CVE-2026-88099 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows Server 2019
- CVE-2026-88102 Microsoft Failover Cluster Remote Code Execution Vulnerability
- CVE-2026-102192 Windows Failover Cluster Denial of Service Vulnerability
- CVE-2026-69577 Microsoft Azure Attestation service and Device Health Attestation Service Information Disclosure Vulnerability
- CVE-2026-96945 Windows Failover Cluster Denial of Service Vulnerability
- CVE-2026-21243 Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability
Sources
Also known as GHSA-hh53-6rv7-rjrv.