Microsoft Security Response CenterCVE-2026-27927

Windows Projected File System Elevation of Privilege Vulnerability

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Projected File System allows an authorized attacker to elevate privileges locally.

Read the vendor bulletin Get alerts for Windows Server 2022 (Server Core installation)

7.8CVSS out of 10High severity

Scope

What the vendor says is affected

Windows Server 2022 (Server Core installation)
Windows Server 2022
Windows 10 Version 1809 for 32-bit Systems
Windows 10 Version 21H2 for 32-bit Systems
Windows 10 Version 21H2 for ARM64-based Systems
Windows 10 Version 1809 for x64-based Systems
Windows 10 Version 21H2 for x64-based Systems
Windows 10 Version 22H2 for x64-based Systems
Windows Server 2019 (Server Core installation)
Windows Server 2019
Windows 10 Version 22H2 for ARM64-based Systems
Windows 10 Version 22H2 for 32-bit Systems
Windows Server 2025 (Server Core installation)
Windows 11 Version 25H2 for ARM64-based Systems
Windows 11 Version 23H2 for x64-based Systems
Windows 11 Version 25H2 for x64-based Systems
Windows 11 Version 23H2 for ARM64-based Systems
Windows Server 2022, 23H2 Edition (Server Core installation)
Windows 11 Version 24H2 for ARM64-based Systems
Windows 11 Version 24H2 for x64-based Systems
Windows Server 2025
Windows 11 Version 26H1 for ARM64-based Systems
Windows 11 version 26H1 for x64-based Systems

Versions the vendor lists as fixed

10.0.20348.5020
10.0.17763.8644
10.0.19044.7184
10.0.19045.7184
10.0.26100.32690
10.0.26200.8246
10.0.22631.6936
10.0.25398.2274
10.0.26100.8246
10.0.28000.1836

Next step

What the vendor recommends

Install KB5082142. Install KB5082123. Install KB5082200. Install KB5082063. Install KB5083769. Install KB5082052. Install KB5082060. Install KB5083768.

Review the complete instructions on the vendor's site

Timeline

When this advisory changed

Apr 14, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Sep 27, 2026 at 11:11 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.

Vulnerabilities

CVEs named in this advisory

CVE-2026-27927View CVSS, KEV, EPSS, and threat context

Source

Start with the vendor's bulletin

SecurityAlert organizes the fields the vendor published. The original bulletin remains the source of record for affected versions, fixes, and later changes.

Vendor: Microsoft Security Response Center
Advisory ID: CVE-2026-27927
Last source check: Sep 27, 2026 at 11:11 PM UTC

Open the official bulletin How SecurityAlert builds this record

Your environment

Check the systems you actually run

A vendor advisory can tell you what may be affected. It cannot tell you whether that product and version are installed in your environment.

Confirm the product and installed version.
Read the vendor's prerequisites and exceptions.
Test the update or mitigation through your normal change process.

Watch Windows Server 2022 (Server Core installation)

Keep following

Get new Microsoft Security Response Center advisories

Use the vendor-specific RSS feed or set up alerts for a product your team relies on.

Follow this vendor's RSS feed

What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

When this advisory changed

CVEs named in this advisory

Related advisories from Microsoft Security Response Center

Chromium CVE-2026-95385: Inappropriate implementation in PlatformIntegration

Chromium CVE-2026-95384: Race condition in Transactions Platform

Chromium CVE-2026-95382: Improper input validation in Auth

Chromium CVE-2026-95381: Improper input validation in Printing

Chromium CVE-2026-95380: Type confusion in V8

Chromium CVE-2026-95376: Externally controlled reference in DevTools