Microsoft's Windows 10 Update Fixes 1,235 Vulnerabilities, Including Outlook Flaw
Microsoft's KB5131096 update for Windows 10, released on November 10, 2026, addresses 1,235 vulnerabilities and enhances PowerShell script security.
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What happened
Microsoft released the Windows 10 KB5131096 security update.
Who is affected
Windows 10 and Windows 10 Enterprise LTSC 2021.
Exploited
Scripts with invalid UTF-8 encoding might fail signature validation.
What to do
Review affected scripts, save with valid UTF-8 encoding, and sign again.
Microsoft released the Windows 10 KB5131096 extended security update on November 10, 2026. This update addresses 1,235 vulnerabilities across various Microsoft products, including an actively exploited zero-day flaw in Outlook.
The update enhances security for PowerShell scripts by introducing stricter encoding validation for script signing and signature verification. As a result, scripts with invalid UTF-8 encoding may fail signature validation after the update.
Microsoft advises users to review affected scripts, ensure they are saved with valid UTF-8 encoding with a byte order mark (BOM), and sign them again to maintain functionality.
The update brings Windows 10 to build 19045.7846 and Windows 10 Enterprise LTSC 2021 to build 19044.7846. It primarily contains security updates and bug fixes, as Microsoft no longer releases new features for Windows 10.
