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Medium severity · published Oct 13, 2026
CVE-2026-97790
Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability
5.5
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 32% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
W1
Windows 11 Version 24H2 · Microsoft
10.0.26100.0 before 10.0.26100.9711 · source: vendor
W1
Windows 11 Version 25H2 · Microsoft
10.0.26200.0 before 10.0.26200.9711 · source: vendor
W1
Windows 11 Version 26H2 · Microsoft
10.0.26300.0 before 10.0.26300.9711 · source: vendor
W1
Windows 11 version 26H1 · Microsoft
10.0.28000.0 before 10.0.28000.3231 · source: vendor
WS
Windows Server 2022 · Microsoft
10.0.20348.0 before 10.0.20348.5761 · source: vendor, NVD
WS
Windows Server 2025 · Microsoft
10.0.26100.0 before 10.0.26100.33650 · source: vendor, NVD
WS
Windows Server 2025 (Server Core installation) · Microsoft
10.0.26100.0 before 10.0.26100.33650 · source: vendor
W1
Windows 11 24h2 · Microsoft
before 10.0.26100.9711; before 10.0.26100.9711 · source: NVD
W1
Windows 11 25h2 · Microsoft
before 10.0.26200.9711; before 10.0.26200.9711 · source: NVD
W1
Windows 11 26h1 · Microsoft
before 10.0.28000.3231; before 10.0.28000.3231 · source: NVD
W1
Windows 11 26h2 · Microsoft
before 10.0.26300.9711; before 10.0.26300.9711 · source: NVD
Affected product
W1
Windows 11 Version 24H2
Microsoft
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-97790
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-97790
vendor-advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97790
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