CVE-2026-88099Network attack vector

Unauthenticated denial of service via uncaught exception

Published Oct 13, 2026 · Updated Oct 13, 2026

Uncaught exceptions in Microsoft Windows Server Failover Cluster allow remote attackers to interrupt service through network access. The published record does not disclose the failing handler, triggering input, or whether disruption is a crash or hang. Windows Server 2019, 2022, and 2025, including the listed Server Core variants, are affected; exploitation requires network reachability without authentication.

CVSS severity5.9
Medium
EPSS probability0.82%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncaught exceptions in Microsoft Windows Server Failover Cluster allow remote attackers to interrupt service through network access. The published record does not disclose the failing handler, triggering input, or whether disruption is a crash or hang. Windows Server 2019, 2022, and 2025, including the listed Server Core variants, are affected; exploitation requires network reachability without authentication.

The record

CVE
CVE-2026-88099
Published
Oct 13, 2026
Updated
Oct 13, 2026
Vendor
Microsoft Corporation
Product
Windows Server 2019
Classifications
CWE-248, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.17763.0 <10.0.17763.9376

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft Corporation · Windows Server 2019version=10.0.17763.0 <10.0.17763.9376
Microsoft Corporation · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.33650
Microsoft Corporation · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.9376
Microsoft Corporation · Windows Server 2022version=10.0.20348.0 <10.0.20348.5761
Microsoft Corporation · Windows Server 2025version=10.0.26100.0 <10.0.26100.33650

Published CVSS scores

5.9MicrosoftCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-248Uncaught Exception
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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