Disclosure summary
Heap-based buffer overflow in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to elevate privileges locally.
Source-reported weakness categories
CWE-122
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
Microsoft Security Updates (CVRF) · 2026-Aug
Open original source · Updated Sep 15, 2026
Windows Container Isolation FS Filter Driver (unionfs.sys) Elevation of Privilege Vulnerability
Maximum of vendor-reported product scores; products and fixed builds are associations, not a universal affected-version statement.
Microsoft maximum product score: 7.8
| Vendor | Product / association | Version / bounds |
|---|---|---|
| Microsoft update guide | Windows 11 version 26H1 for x64-based Systems | (MSRC status code 3) |
| Microsoft update guide | Windows 11 Version 26H1 for ARM64-based Systems | (MSRC status code 3) |
Vendor remediation references
- 5121000 · build 10.0.28000.2704 · product IDs 20853, 20854
- Vendor guidance · product IDs 20853, 20854
Original records & references
- NIST NVD record
- CVE Program record
- msrc.microsoft.com — Vendor advisory
PUBLISHED 2026-08-11T03:00:00-04:00
MODIFIED 2026-09-15T03:00:00-04:00
INGESTED 2026-10-08T12:40:35-04:00