PatchTheCEVCVE-2026-62772: Heap-based buffer overflow in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized
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Routine
HIGH 7.8WATCHLISTUPGRADE
CVE-2026-62772 is a high-severity flaw (CVSS 7.8) affecting windows 11 26h1. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Heap-based buffer overflow in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to elevate privileges locally.
Why this priority
- High severity
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.8 (High) |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 0.3% (top 75%) |
| CISA exploited list | No |
| Weakness | CWE-122 |
| Published | 2026-08-11 |
| Last modified | 2026-10-23 |
Publisher (CNA): Microsoft Corporation · Vendor: microsoft
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
microsoft windows 11 26h1 UPGRADE
Affected: < 10.0.28000.2704
Fixed in: 10.0.28000.2704
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Exact fixes by distribution
Fedora 46 · clementine · FIXED · 1.4.2-1.fc46 · FEDORA-2026-3e748ef4d3 · source
sudo dnf upgrade --advisory=FEDORA-2026-3e748ef4d3
Windows 11 version 26H1 for x64-based Systems · KB5121000 · FIXED · 10.0.28000.2704 · KB5121000 · source
Install KB5121000 via Windows Update, then verify:
Get-HotFix -Id KB5121000
Windows 11 Version 26H1 for ARM64-based Systems · KB5121000 · FIXED · 10.0.28000.2704 · KB5121000 · source
Install KB5121000 via Windows Update, then verify:
Get-HotFix -Id KB5121000
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
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