What is CVE-2026-20859?

CVE-2026-20859 is a security advisory published by Microsoft Security Response Center (MSRC) with High severity. Windows Kernel-Mode Driver Elevation of Privilege Vulnerability

Which CVE IDs does CVE-2026-20859 cover?

CVE-2026-20859 covers the following CVE IDs: CVE-2026-20859. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-20859?

CVE-2026-20859 has a CVSS v3 base score of 7.8, published by Microsoft Security Response Center (MSRC).

Which products are affected by CVE-2026-20859?

CVE-2026-20859 affects 6 products, including: Windows 11 Version 24H2 for ARM64-based Systems; Windows 11 Version 24H2 for x64-based Systems; Windows 11 Version 25H2 for ARM64-based Systems; Windows 11 Version 25H2 for x64-based Systems; Windows Server 2025; and others — see the full list on the advisory page.

CVE-2026-20859HighCVSS 7.8

Windows Kernel-Mode Driver Elevation of Privilege Vulnerability

Vendor

Microsoft Security Response Center (MSRC)

Published

June 2, 2026

Last Modified

—

🔗 CVE IDs covered (1)

CVE-2026-20859 →

📋 Description

Use after free in Windows Kernel-Mode Drivers allows an authorized attacker to elevate privileges locally.

🎯 Affected products6

Windows 11 Version 24H2 for ARM64-based Systems
Windows 11 Version 24H2 for x64-based Systems
Windows 11 Version 25H2 for ARM64-based Systems
Windows 11 Version 25H2 for x64-based Systems
Windows Server 2025
Windows Server 2025 (Server Core installation)

✅ Remediation

KB5073379 (Security Update) — fixed build 10.0.26100.32230 KB5074109 (Security Update) — fixed build 10.0.26200.7623 KB5074109 (Security Update) — fixed build 10.0.26100.7623

🔗 References (6)

advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20859
patchhttps://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5073379
referencehttps://support.microsoft.com/en-us/topic/a6021fd2-b3b7-45a7-b68e-35c28a2a77da
referencehttps://support.microsoft.com/help/5073379
patchhttps://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5074109
referencehttps://support.microsoft.com/help/5074109