Review reviewHigh

CVE-2026-40409

Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows 10 Version 21H2

Windows Universal Disk Format File System Driver (UDFS) Elevation of Privilege Vulnerability

PRIORITY ASSESSMENT

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.30%

Technical severityCVSS 7.8

Windows Universal Disk Format File System Driver (UDFS) Elevation of Privilege Vulnerability

Product: Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows 10 Version 21H2
Affected versions: >= 10.0.14393.0 < 10.0.14393.9234, >= 10.0.17763.0 < 10.0.17763.8880, >= 10.0.19044.0 < 10.0.19044.7417, >= 10.0.19045.0 < 10.0.19045.7417, >= 10.0.22631.0 < 10.0.22631.7219, >= 10.0.26100.0 < 10.0.26100.8655, >= 10.0.26200.0 < 10.0.26200.8655, >= 10.0.28000.0 < 10.0.28000.2269, >= 6.2.9200.0 < 6.2.9200.26132, >= 6.3.9600.0 < 6.3.9600.23228, >= 10.0.20348.0 < 10.0.20348.5256, >= 10.0.26100.0 < 10.0.26100.32995, < 10.0.14393.9234, < 10.0.17763.8880, < 10.0.19044.7417, < 10.0.19045.7417, < 10.0.22631.7219, < 10.0.26100.8655, < 10.0.26200.8655, < 10.0.28000.2269
Fixed versions: 10.0.14393.9234, 10.0.17763.8880, 10.0.19044.7417, 10.0.19045.7417, 10.0.22631.7219, 10.0.26100.8655, 10.0.26200.8655, 10.0.28000.2269, 10.0.20348.5256, 10.0.26100.32995

Confirm exposure before applying a vendor-supported change.

1
Identify
Confirm that Microsoft Windows 10 Version 1607, Windows 10 Version 1809, Windows 10 Version 21H2 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.