Zscaler protects against 9 new vulnerabilities for Windows

Zscaler, working with Microsoft through their MAPP program, has proactively deployed protection for the following 9 vulnerabilities included in the January 2026 Microsoft security bulletins. Zscaler will continue to monitor exploits associated with all vulnerabilities in the January release and deploy additional protections, as necessary.

CVE-2026-20805 – Desktop Window Manager Information Disclosure Vulnerability

Severity: Important

Subscriptions Required

Affected Software

• Windows 10 Version 1809 for x64-based Systems
• Windows 10 Version 1809 for 32-bit Systems
• Windows Server 2012 R2 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 (Server Core installation)
• Windows Server 2012
• Windows Server 2016 (Server Core installation)
• Windows Server 2016
• Windows 10 Version 1607 for x64-based Systems
• Windows 10 Version 1607 for 32-bit Systems
• Windows Server 2025
• Windows 11 Version 24H2 for x64-based Systems
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 23H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 22H2 for 32-bit Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for x64-based Systems
• Windows 10 Version 21H2 for x64-based Systems
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for 32-bit Systems
• Windows Server 2022 (Server Core installation)
• Windows Server 2022
• Windows Server 2019 (Server Core installation)
• Windows Server 2019

CVE-2026-20816 – Windows Installer Elevation of Privilege Vulnerability

Severity: Important

Subscriptions Required

Affected Software

• Windows Server 2012 R2 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 (Server Core installation)
• Windows Server 2012
• Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
• Windows Server 2008 R2 for x64-based Systems Service Pack 1
• Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for x64-based Systems Service Pack 2
• Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for 32-bit Systems Service Pack 2
• Windows Server 2016 (Server Core installation)
• Windows Server 2016
• Windows 10 Version 1607 for x64-based Systems
• Windows 10 Version 1607 for 32-bit Systems
• Windows Server 2025
• Windows 11 Version 24H2 for x64-based Systems
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 23H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 22H2 for 32-bit Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for x64-based Systems
• Windows 10 Version 21H2 for x64-based Systems
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for 32-bit Systems
• Windows Server 2022 (Server Core installation)
• Windows Server 2022
• Windows Server 2019 (Server Core installation)
• Windows Server 2019
• Windows 10 Version 1809 for x64-based Systems
• Windows 10 Version 1809 for 32-bit Systems

CVE-2026-20817 – Windows Error Reporting Service Elevation of Privilege Vulnerability

Severity: Important

Subscriptions Required

Affected Software

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

CVE-2026-20820 – Windows Common Log File System Driver Elevation of Privilege Vulnerability

Severity: Important

Subscriptions Required

Affected Software

• Windows Server 2012 R2 (Server Core installation)
• Windows Server 2012 (Server Core installation)
• Windows Server 2008 for 32-bit Systems Service Pack 2
• Windows Server 2016
• Windows Server 2012 R2
• Windows 10 Version 1607 for 32-bit Systems
• Windows Server 2012
• Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
• Windows Server 2008 for x64-based Systems Service Pack 2
• Windows Server 2008 R2 for x64-based Systems Service Pack 1
• Windows Server 2016 (Server Core installation)
• Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
• Windows 10 Version 1607 for x64-based Systems
• Windows Server 2025
• Windows 11 Version 24H2 for x64-based Systems
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows 11 Version 23H2 for x64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for x64-based Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 10 Version 22H2 for 32-bit Systems
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 21H2 for x64-based Systems
• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2019 (Server Core installation)
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for 32-bit Systems
• Windows Server 2022
• Windows Server 2019
• Windows 10 Version 1809 for 32-bit Systems
• Windows Server 2022 (Server Core installation)

CVE-2026-20840 – Windows NTFS Remote Code Execution Vulnerability

Severity: Important

Subscriptions Required

Affected Software

• Windows 11 Version 24H2 for x64-based Systems
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 23H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 22H2 for 32-bit Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for x64-based Systems
• Windows 10 Version 21H2 for x64-based Systems
• Windows Server 2012 R2 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 (Server Core installation)
• Windows Server 2012
• Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
• Windows Server 2008 R2 for x64-based Systems Service Pack 1
• Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for x64-based Systems Service Pack 2
• Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for 32-bit Systems Service Pack 2
• Windows Server 2016 (Server Core installation)
• Windows Server 2016
• Windows 10 Version 1607 for x64-based Systems
• Windows 10 Version 1607 for 32-bit Systems
• Windows Server 2025
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for 32-bit Systems
• Windows Server 2022 (Server Core installation)
• Windows Server 2022
• Windows Server 2019 (Server Core installation)
• Windows Server 2019
• Windows 10 Version 1809 for x64-based Systems
• Windows 10 Version 1809 for 32-bit Systems

CVE-2026-20843 – Windows Routing and Remote Access Service (RRAS) Elevation of Privilege Vulnerability

Severity: Important

Subscriptions Required

Affected Software

• Windows Server 2012 R2 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 (Server Core installation)
• Windows Server 2012
• Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
• Windows Server 2008 R2 for x64-based Systems Service Pack 1
• Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for x64-based Systems Service Pack 2
• Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for 32-bit Systems Service Pack 2
• Windows Server 2016 (Server Core installation)
• Windows Server 2016
• Windows 10 Version 1607 for x64-based Systems
• Windows 10 Version 1607 for 32-bit Systems
• Windows Server 2025
• Windows 11 Version 24H2 for x64-based Systems
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 23H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 22H2 for 32-bit Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for x64-based Systems
• Windows 10 Version 21H2 for x64-based Systems
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for 32-bit Systems
• Windows Server 2022 (Server Core installation)
• Windows Server 2022
• Windows Server 2019 (Server Core installation)
• Windows Server 2019
• Windows 10 Version 1809 for x64-based Systems
• Windows 10 Version 1809 for 32-bit Systems

CVE-2026-20860 – Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Severity: Important

Subscriptions Required

Affected Software

• Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for x64-based Systems Service Pack 2
• Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
• Windows Server 2008 for 32-bit Systems Service Pack 2
• Windows Server 2016 (Server Core installation)
• Windows Server 2016
• Windows 10 Version 1607 for x64-based Systems
• Windows 10 Version 1607 for 32-bit Systems
• Windows Server 2025
• Windows 11 Version 24H2 for x64-based Systems
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 23H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 22H2 for 32-bit Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for x64-based Systems
• Windows 10 Version 21H2 for x64-based Systems
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 10 Version 21H2 for 32-bit Systems
• Windows Server 2022 (Server Core installation)
• Windows Server 2022
• Windows Server 2019 (Server Core installation)
• Windows Server 2019
• Windows 10 Version 1809 for x64-based Systems
• Windows 10 Version 1809 for 32-bit Systems

CVE-2026-20871 – Desktop Windows Manager Elevation of Privilege Vulnerability

Severity: Important

Subscriptions Required

Affected Software

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

CVE-2026-20922 – Windows NTFS Remote Code Execution Vulnerability

Severity: Important

Subscriptions Required

Affected Software

• Windows Server 2012 R2 (Server Core installation)
• Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
• Windows Server 2012
• Windows Server 2008 for x64-based Systems Service Pack 2
• Windows Server 2008 for 32-bit Systems Service Pack 2
• Windows Server 2016
• Windows Server 2012 (Server Core installation)
• Windows Server 2019
• Windows Server 2008 R2 for x64-based Systems Service Pack 1
• Windows 10 Version 1809 for 32-bit Systems
• Windows 10 Version 22H2 for ARM64-based Systems
• Windows 10 Version 22H2 for x64-based Systems
• Windows Server 2016 (Server Core installation)
• Windows 10 Version 1607 for x64-based Systems
• Windows 10 Version 1607 for 32-bit Systems
• Windows Server 2012 R2
• Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
• Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
• Windows 11 Version 24H2 for x64-based Systems
• Windows Server 2025
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 23H2 for x64-based Systems
• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 25H2 for x64-based Systems
• Windows 10 Version 21H2 for ARM64-based Systems
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows Server 2022
• Windows 10 Version 22H2 for 32-bit Systems
• Windows Server 2025 (Server Core installation)
• Windows 10 Version 21H2 for x64-based Systems
• Windows Server 2019 (Server Core installation)
• Windows 10 Version 21H2 for 32-bit Systems
• Windows Server 2022 (Server Core installation)