Description
Uncaught exception in Windows Failover Cluster allows an unauthorized attacker to deny service over a network.
Published: 2026-10-13
Score: 5.9 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service via Failover Cluster
Action: Immediate Patch
AI Analysis

Impact

An uncaught exception in the Windows Failover Cluster can be triggered by an unauthenticated attacker over the network, causing the cluster to enter an unusable state. The vulnerability’s primary effect is a denial of service that disrupts the availability of clustered services, potentially impacting critical infrastructure that relies on Windows Server Failover Cluster for high availability.

Affected Systems

Microsoft Windows Server 2019, Windows Server 2019 Server Core, Windows Server 2022, Windows Server 2025, and Windows Server 2025 Server Core are affected.

Risk and Exploitability

The CVSS score of 5.9 indicates a moderate risk. The EPSS score is below 1%, and the vulnerability is not listed in the CISA KEV catalog. An attacker can exploit this flaw remotely via normal cluster communication protocols without requiring elevated privileges, making it accessible to anyone with network reach to the cluster.

Generated by OpenCVE AI on October 16, 2026 at 23:11 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Install the latest Windows Server cumulative update that contains the fix for CVE-2026-88099 on all Failover Cluster nodes.
  • If immediate patching is not possible, isolate the cluster from external network traffic, such as moving the nodes to a separate internal subnet or blocking external ports.
  • Configure the Windows Firewall or network segmentation to restrict cluster communication to trusted internal interfaces, ensuring only authorized nodes can communicate within the cluster.

Generated by OpenCVE AI on October 16, 2026 at 23:11 UTC.

Tracking

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Advisories

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History

Fri, 16 Oct 2026 16:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:x64:*

Thu, 15 Oct 2026 20:00:00 +0000

Type Values Removed Values Added
First Time appeared Microsoft windows Server 2019 (server Core Installation)
Microsoft windows Server 2025 (server Core Installation)
Vendors & Products Microsoft windows Server 2019 (server Core Installation)
Microsoft windows Server 2025 (server Core Installation)

Wed, 14 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 13 Oct 2026 19:15:00 +0000

Type Values Removed Values Added
Description Uncaught exception in Windows Failover Cluster allows an unauthorized attacker to deny service over a network.
Title Windows Failover Cluster Denial of Service Vulnerability
First Time appeared Microsoft
Microsoft windows Server 2019
Microsoft windows Server 2022
Microsoft windows Server 2025
Weaknesses CWE-248
CPEs cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*
Vendors & Products Microsoft
Microsoft windows Server 2019
Microsoft windows Server 2022
Microsoft windows Server 2025
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C'}

Subscriptions

Microsoft Windows Server 2019 Windows Server 2019 (server Core Installation) Windows Server 2022 Windows Server 2025 Windows Server 2025 (server Core Installation)
cve-icon MITRE

Status: PUBLISHED

Assigner: microsoft

Published:

Updated: 2026-10-31T18:05:54.016Z

Reserved: 2026-09-09T21:51:51.953Z

Link: CVE-2026-88099

cve-icon Vulnrichment

Updated: 2026-10-13T19:58:11.012Z

cve-icon NVD

Status : Analyzed

Published: 2026-10-13T19:21:27.800

Modified: 2026-10-16T15:43:48.160

Link: CVE-2026-88099

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-16T23:15:14Z

Weaknesses