# CVE-2026-88099: Windows Failover Cluster uncaught exception denial of service

Source: https://junglewise.ai/threats/cve-2026-88099-uncaught-exception-in-windows-failover-cluster-allows-an  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-88099 · Severity: medium · CVSS 5.9 · Published 2026-10-13

Windows Failover Cluster, which manages redundant servers in enterprise environments, contains an uncaught exception vulnerability that allows an unauthenticated attacker to trigger a denial of service over the network. An exploit would disrupt cluster operations and the services running on it, potentially causing business-critical downtime.

Technologies: [Microsoft Windows Failover Cluster](https://junglewise.ai/threats/technologies/windows-failover-cluster), [Microsoft Windows Server 2019](https://junglewise.ai/threats/technologies/windows-server-2019), [Microsoft Windows Server 2022](https://junglewise.ai/threats/technologies/windows-server-2022), [Microsoft Windows Server 2025](https://junglewise.ai/threats/technologies/windows-server-2025). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-88099 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88099 being exploited in the wild.

**How severe is CVE-2026-88099?** Medium severity, with a CVSS score of 5.9, published 13 October 2026.

**Which products and versions are affected?** Microsoft Windows Failover Cluster.

**Is there a fix for CVE-2026-88099?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-88099 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-88099?** Check whether you run Microsoft Windows Failover Cluster, Microsoft Windows Server 2019, Microsoft Windows Server 2022 or one of the others listed. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An uncaught exception in Windows Failover Cluster can be triggered remotely by an unauthenticated attacker over the network, leading to denial of service. The vulnerability allows an attacker to crash or hang cluster resources without prior authentication or user interaction. A patch is expected from Microsoft.

## Affected products

- Microsoft Windows Failover Cluster

## Timeline

- 2026-10-13: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-88099](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-88099)

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