CVE-2026-102202: Windows Container Isolation FS Filter Driver (unionfs.sys) Elevation of Privilege Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-13 · updated 2026-10-31
Weakness: CWE-59

Description

Improper access control in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to elevate privileges locally.

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 10.0.22631.0 before 10.0.22631.7652 — fixed in 10.0.22631.7652
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.9711 — fixed in 10.0.26100.9711
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.9711 — fixed in 10.0.26200.9711
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.3231 — fixed in 10.0.28000.3231
Microsoft Windows 11 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

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 10.0.22631.7652; 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. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-102202

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