---
id: CVE-2026-97790
title: >-
  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.
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.
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-59
vendor: microsoft
product: windows_11_24h2
affected:
  - windows_11_24h2 < 10.0.26100.9711
  - windows_11_25h2 < 10.0.26200.9711
  - windows_11_26h1 < 10.0.28000.3231
  - windows_11_26h2 < 10.0.26300.9711
  - windows_server_2022 < 10.0.20348.5761
  - windows_server_2025 < 10.0.26100.33650
patched:
  - windows_11_24h2 10.0.26100.9711
  - windows_11_25h2 10.0.26200.9711
  - windows_11_26h1 10.0.28000.3231
  - windows_11_26h2 10.0.26300.9711
  - windows_server_2022 10.0.20348.5761
  - windows_server_2025 10.0.26100.33650
published: '2026-10-13'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T10:40:56.477'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97790'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-97790'
    label: secure@microsoft.com
tags:
  - nvd
  - cve.org
epss: 0.00385
epssPercentile: 0.32401
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-13T19:31:32.288553Z'
ingestedAt: '2026-10-13T19:43:29.306Z'
---

## Overview

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.

## Affected

- `windows_11_24h2 < 10.0.26100.9711`
- `windows_11_25h2 < 10.0.26200.9711`
- `windows_11_26h1 < 10.0.28000.3231`
- `windows_11_26h2 < 10.0.26300.9711`
- `windows_server_2022 < 10.0.20348.5761`
- `windows_server_2025 < 10.0.26100.33650`

## Remediation

Upgrade past the affected range:

- `windows_11_24h2 10.0.26100.9711`
- `windows_11_25h2 10.0.26200.9711`
- `windows_11_26h1 10.0.28000.3231`
- `windows_11_26h2 10.0.26300.9711`
- `windows_server_2022 10.0.20348.5761`
- `windows_server_2025 10.0.26100.33650`