Back to vendor advisories
Microsoft Security Response CenterCVE-2026-21530

Windows Rich Text Edit Elevation of Privilege Vulnerability

HighVendor CVSS 6.7 / 10 1 CVE Published May 12, 2026 at 7:00 AM UTC

Summary

Double free in Windows Rich Text Edit allows an authorized attacker to elevate privileges locally.

Products covered

  • Windows 10 Version 1809 for 32-bit Systems

  • Windows 10 Version 1809 for x64-based Systems

  • Windows Server 2019

  • Windows Server 2019 (Server Core installation)

  • Windows Server 2022

  • Windows Server 2022 (Server Core installation)

  • Windows 10 Version 21H2 for 32-bit Systems

  • Windows 10 Version 21H2 for ARM64-based Systems

Show 33 more products
  • Windows 10 Version 21H2 for x64-based Systems

  • Windows 10 Version 22H2 for x64-based Systems

  • 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 25H2 for x64-based Systems

  • Windows 11 Version 23H2 for ARM64-based Systems

  • Windows 11 Version 23H2 for x64-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 x64-based Systems

  • Windows 11 Version 26H1 for ARM64-based Systems

  • Windows 10 Version 1607 for 32-bit Systems

  • Windows 10 Version 1607 for x64-based Systems

  • Windows Server 2016

  • Windows Server 2016 (Server Core installation)

  • Windows Server 2012

  • Windows Server 2012 (Server Core installation)

  • Windows Server 2012 R2

  • Windows Server 2012 R2 (Server Core installation)

  • Microsoft Office 2019 for 32-bit editions

  • Microsoft Office 2019 for 64-bit editions

  • Microsoft 365 Apps for Enterprise for 32-bit Systems

  • Microsoft 365 Apps for Enterprise for 64-bit Systems

  • Microsoft Office LTSC 2021 for 64-bit editions

  • Microsoft Office LTSC 2021 for 32-bit editions

  • Microsoft Office LTSC 2024 for 32-bit editions

  • Microsoft Office LTSC 2024 for 64-bit editions

  • Microsoft Office 2016 (32-bit edition)

  • Microsoft Office 2016 (64-bit edition)

Remediation

Click to Run Install KB5087538. Install KB5087545. Install KB5087424. Install KB5087544. Install KB5094127. Install KB5087539. Install KB5087423. Install KB5089549. Install KB5089466. Install KB5087420. Install KB5093998. Install KB5087541. Install KB5089548. Install KB5087537. Install KB5087470. Install KB5087471. Install KB5002578.

Vendor-listed fixes

  • 10.0.17763.8755

  • 10.0.20348.5139

  • 10.0.20348.5074

  • 10.0.19044.7291

  • 10.0.19045.7417

  • 10.0.26100.32860

  • 10.0.26100.32772

  • 10.0.26200.8457

Show 12 more fixes
  • 10.0.26200.8390

  • 10.0.22631.7079

  • 10.0.22631.7219

  • 10.0.25398.2330

  • 10.0.26100.8457

  • 10.0.26100.8390

  • 10.0.28000.2113

  • 10.0.14393.9140

  • 6.2.9200.26079

  • 6.3.9600.23181

  • https://aka.ms/OfficeSecurityReleases

  • 16.0.5556.1000

CVEs in this advisory 1

Updates

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Updated by Microsoft Security Response Center

    The vendor changed the advisory after it was first published.

  3. Added to SecurityAlert

    We collected the advisory from the official source.

  4. Confirmed at the source

    Our collector saw this advisory during a later source check.