High MSRC-CVE-2026-97790 1 CVE

Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability

Published Oct 13, 2026 · Updated Oct 13, 2026

Vendor: Microsoft

Summary

Impact: Tampering. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.

Details

Security updates
10.0.20348.5761 — https://support.microsoft.com/help/5126655
10.0.26100.9711 — https://support.microsoft.com/help/5127648
10.0.26100.33650 — https://support.microsoft.com/help/5126646
10.0.28000.3231 — https://support.microsoft.com/help/5127646

Vulnerabilities 1

Medium 5.5

CVE-2026-97790

Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability

Improper link resolution before file access ('link following') in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to perform tampering locally.

Microsoft Windows Server 2022 Windows Server 2025 Windows Server 2025 (Server Core installation) Windows

Oct 13, 2026

Revision history

2026-10-13 #1
Information published.

References

CVE-2026-97790 Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97790
Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
Common Vulnerability Scoring System
https://www.first.org/cvss