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.
Other sources
Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26200.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33650Patch KB5126646 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26300.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.9711Patch KB5127648 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.20348.5761Patch KB5126655 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.28000.3231Patch KB5127646
Event History
Frequently Asked Questions
Does exploitation require remote access or user interaction?
No. The vulnerability is rated for local attack access and requires no user interaction.
What level of access does an attacker need?
The attacker must already be authorized with low privileges on the affected system.
Which systems are identified as affected?
The affected software list includes Microsoft Windows 11, Microsoft Windows Server 2022, Microsoft Windows Server 2025, and the Microsoft Windows Container Isolation FS Filter Driver.