---
id: CVE-2026-62772
title: >-
  Windows Container Isolation FS Filter Driver (unionfs.sys) Elevation of
  Privilege Vulnerability
summary: >-
  Heap-based buffer overflow in Windows Container Isolation FS Filter Driver
  (unionfs.sys) allows an authorized attacker to elevate privileges locally.
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C'
cvssSource: cna
cwe:
  - CWE-122
vendor: Microsoft
product: Windows 11 version 26H1
affected:
  - windows_11_version_26h1 >= 10.0.28000.0 < 10.0.28000.2704
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-08-12T13:39:06.890688Z'
published: '2026-08-11'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T13:44:44.298Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-62772'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62772'
    label: >-
      Windows Container Isolation FS Filter Driver (unionfs.sys) Elevation of
      Privilege Vulnerability
tags:
  - cve.org
epss: 0.00333
epssPercentile: 0.23882
ingestedAt: '2026-09-08T18:07:34.898Z'
---

## Overview

Heap-based buffer overflow in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to elevate privileges locally.

## Affected

- `windows_11_version_26h1 >= 10.0.28000.0 < 10.0.28000.2704`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.