WORLDTECHMicrosoft ships Windows 10 security update fixing 1,235 flaws, including Outlook zero-day
Microsoft has released the Windows 10 KB5131096 extended security update, carrying the November 2026 Patch Tuesday fixes along with several bug resolutions and system adjustments. The release addresses 1,235 vulnerabilities across the Microsoft ecosystem, among them a critical Outlook zero-day.
Build numbers and who can install
The patch raises Windows 10 to build 19045.7846 and Windows 10 Enterprise LTSC 2021 to build 19044.7846. Users running Windows 10 Enterprise LTSC, as well as those enrolled in the Extended Security Update program, can obtain the update through Windows Update.
Microsoft is a software and software development company based in Redmond, and its products and services include Microsoft Windows.
Scope of the vulnerability fixes
According to the report, the release addresses 1,235 vulnerabilities across the Microsoft ecosystem. The most serious is a critical Outlook flaw that is a zero-day, meaning it was already being exploited in attacks before a fix existed.
Smaller fixes and stability work
Among the notable changes, the update revises daylight saving time rules for Cuba and corrects a printing error that had caused failures when adding Active Directory printers. It also resolves Remote Desktop shadow connection errors.
Security for PowerShell script signing is tightened through stricter encoding validation. Microsoft has additionally dealt with remaining problems affecting USB Audio Class 1.0 devices, which had led to audio failures and unresponsive volume controls after the September 2026 security updates.
The fixes are intended to improve stability for enterprises that still depend on legacy Windows 10 support.
Open questions
- Has the Outlook zero-day been exploited against organisations, and how widely?