Windows Container Isolation FS Filter Driver (unionfs.sys)
CVE-2026-72971 — Windows Container Isolation FS Filter Driver (unionfs.sys) Tampering Vulnerability
Executive Summary
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.
Overview
5.5
CVSS MEDIUM
Important
MS Severity
Not Exploited
MS Exploit Status
Exploitation Unlikely
MS Exploit Likelihood
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N/E:U/RL:O/RC:C
ATTACK VECTOR
Local
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
None
INTEGRITY
High
AVAILABILITY
None
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 4.8
EPSS Score
0.00365
probability of exploitation in the next 30 days
0.29527 percentile - updated 2026-08-14
View on FIRST.org
Affected Products
2 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Windows 11 Version 26H1 for ARM64-based Systems | 5121000 (Security Update) |
Important | Tampering | Yes |
| Windows 11 version 26H1 for x64-based Systems | 5121000 (Security Update) |
Important | Tampering | Yes |
Patches
1 patch
| Article | Type | Restart |
|---|---|---|
5121000 |
Security Update | Yes |
Known Exploits
No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.
Acknowledgments
yhw & txz
References
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