---
id: CVE-2026-84009
title: >-
  Time-of-check time-of-use (toctou) race condition in Windows Projected File
  System allows an authorized attacker to perform tampering locally.
summary: >-
  Time-of-check time-of-use (toctou) race condition in Windows Projected File
  System allows an authorized attacker to perform tampering locally.
severity: medium
cvss: 4.7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-367
published: '2026-10-13'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T21:19:09.730'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84009'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-84009'
    label: secure@microsoft.com
tags:
  - nvd
ingestedAt: '2026-10-13T19:43:29.146Z'
---

## Overview

Time-of-check time-of-use (toctou) race condition in Windows Projected File System allows an authorized attacker to perform tampering locally.

## Remediation

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