Security October 2026 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.
Severity Important
CVSS base score 5.9CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
Impact Denial of Service
EPSS, next 30 days 0.8% Higher than 56.9% of scored CVEs · FIRST model run 25 Oct 2026 · about EPSS
Public exploit code No Nuclei template lists it
Exploitability Exploitation Less Likely
Publicly disclosed No
Customer action Required: apply the update
Component Windows Failover Cluster
Weakness CWE-248: Uncaught Exception
Issued by Microsoft
Last revised 13 Oct 2026 CVSS 3.1 base metrics Red raises the risk · green lowers it
Attack vector NetworkAV:N
Attack complexity HighAC:H
Privileges required NonePR:N
User interaction NoneUI:N
Scope UnchangedS:U
Confidentiality NoneC:N
Integrity NoneI:N
Availability HighA:H Source. This summary comes from MSRC's public CVRF document for October 2026. If the MSRC page is blocked in your browser, the NVD and CVE.org records carry the same identifier. None of this says whether your devices are affected.
Explore global source statements, affected packages and advisory history for CVE-2026-88099 . The catalog has a separate collection scope from Microsoft release records.
Overview Affected History Connections
cve-program · CVE-2026-88099 Published Windows Server 2019 Vendor product
Original vendor version evidence · not evaluated as a NuGet range {
"vendor": "Microsoft",
"product": "Windows Server 2019",
"platforms": [
"x64-based Systems"
],
"versions": [
{
"version": "10.0.17763.0",
"lessThan": "10.0.17763.9376",
"versionType": "custom",
"status": "affected"
}
]
} Windows Server 2019 (Server Core installation) Vendor product
Original vendor version evidence · not evaluated as a NuGet range {
"vendor": "Microsoft",
"product": "Windows Server 2019 (Server Core installation)",
"platforms": [
"x64-based Systems"
],
"versions": [
{
"version": "10.0.17763.0",
"lessThan": "10.0.17763.9376",
"versionType": "custom",
"status": "affected"
}
]
} Windows Server 2022 Vendor product
Original vendor version evidence · not evaluated as a NuGet range {
"vendor": "Microsoft",
"product": "Windows Server 2022",
"platforms": [
"x64-based Systems"
],
"versions": [
{
"version": "10.0.20348.0",
"lessThan": "10.0.20348.5761",
"versionType": "custom",
"status": "affected"
}
]
} Windows Server 2025 Vendor product
Original vendor version evidence · not evaluated as a NuGet range {
"vendor": "Microsoft",
"product": "Windows Server 2025",
"platforms": [
"x64-based Systems"
],
"versions": [
{
"version": "10.0.26100.0",
"lessThan": "10.0.26100.33650",
"versionType": "custom",
"status": "affected"
}
]
} Windows Server 2025 (Server Core installation) Vendor product
Original vendor version evidence · not evaluated as a NuGet range {
"vendor": "Microsoft",
"product": "Windows Server 2025 (Server Core installation)",
"platforms": [
"x64-based Systems"
],
"versions": [
{
"version": "10.0.26100.0",
"lessThan": "10.0.26100.33650",
"versionType": "custom",
"status": "affected"
}
]
}