CVE-2026-97830: Windows Internet Information Services Denial of Service Vulnerability

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-13 · updated 2026-10-26
Weakness: CWE-415

Description

Double free in Windows Internet Information Services allows an unauthorized attacker to deny service over a network.

Affected products

Microsoft Windows 11: before 10.0.22631.7652 — fixed in 10.0.22631.7652
Microsoft Windows 11: before 10.0.26100.9711 — fixed in 10.0.26100.9711
Microsoft Windows 11 25H2: before 10.0.26200.9711 — fixed in 10.0.26200.9711
Microsoft Windows 11 version 26H1: before 10.0.28000.3231 — fixed in 10.0.28000.3231
Microsoft Windows 11 26H2: before 10.0.26300.9711 — fixed in 10.0.26300.9711
Microsoft Windows Server 2022: before 10.0.20348.5761 — fixed in 10.0.20348.5761
Microsoft Windows Server 2025: before 10.0.26100.33650 — fixed in 10.0.26100.33650
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.9711 — fixed in 10.0.26100.9711
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.3231 — fixed in 10.0.28000.3231
Microsoft Windows 11 Version 23H2: from 10.0.22631.0 before 10.0.22631.7652 — fixed in 10.0.22631.7652
Microsoft Windows 11 Version 25H2: from 10.0.26200.0 before 10.0.26200.9711 — fixed in 10.0.26200.9711
Microsoft Windows 11 Version 26H2: from 10.0.26300.0 before 10.0.26300.9711 — fixed in 10.0.26300.9711
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.5761 — fixed in 10.0.20348.5761
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.33650 — fixed in 10.0.26100.33650
Microsoft Windows Server 2025 (Server Core installation): from 10.0.26100.0 before 10.0.26100.33650 — fixed in 10.0.26100.33650

How to fix

Upgrade to a fixed version: Microsoft Windows 11 10.0.22631.7652; Microsoft Windows 11 10.0.26100.9711; Microsoft Windows 11 25H2 10.0.26200.9711; Microsoft Windows 11 version 26H1 10.0.28000.3231; Microsoft Windows 11 26H2 10.0.26300.9711; Microsoft Windows Server 2022 10.0.20348.5761; Microsoft Windows Server 2025 10.0.26100.33650; Microsoft Windows 11 10.0.26100.9711; Microsoft Windows 11 version 26H1 10.0.28000.3231; Microsoft Windows 11 Version 23H2 10.0.22631.7652; Microsoft Windows 11 Version 25H2 10.0.26200.9711; Microsoft Windows 11 Version 26H2 10.0.26300.9711. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97830

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