What is CVE-2026-88099?

CVE-2026-88099 is a medium-severity vulnerability in Microsoft Windows Server 2019, classified under CWE-248. CVSS score: 5.9/10. Published 2026-10-13.

How severe is CVE-2026-88099?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Microsoft Windows Server 2019

CVE-2026-88099

Uncaught exception in Windows Failover Cluster allows an unauthorized attacker to deny service over a network.

Published 2026-10-13 · last modified 2026-10-13.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Microsoft Windows Server 2019
Microsoft Windows Server 2019 (Server Core Installation)
Microsoft Windows Server 2022
Microsoft Windows Server 2025
Microsoft Windows Server 2025 (Server Core Installation)

Weakness classification (CWE)

CWE-248

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-88099 (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-88099?: CVE-2026-88099 is a medium-severity vulnerability in Microsoft Windows Server 2019, classified under CWE-248. CVSS score: 5.9/10. Published 2026-10-13.
How severe is CVE-2026-88099?: Medium severity. CVSS v3 base score is 5.9 out of 10.