Microsoft has unveiled its first security updates for 2026, addressing a significant number of vulnerabilities across its Windows operating system and various other products. The January Patch Tuesday initiative tackles over 110 security vulnerabilities, impacting Windows, Microsoft Office, Edge, Azure components, and additional services.
The updates are accessible for all supported versions of Windows. Notably, Windows 10 will continue to receive security fixes exclusively through Microsoft’s Extended Security Updates (ESU) program, while the primary consumer releases benefiting from updates are Windows 11 versions 24H2 and 25H2.
For home users and system administrators, our monthly Patch Day overview offers a succinct summary of the released updates, detailing vulnerability severity, known issues, and direct download resources.
Microsoft Security Updates — January 2026
Executive Summary:
- Microsoft released approximately 112–114 security updates in total
- Around 8 vulnerabilities are rated Critical
- At least one zero-day vulnerability is actively exploited, as confirmed by Microsoft
- Security fixes encompass Windows, Office, Edge, Azure, and server components
Windows clients with known issues
- Windows 11: versions 23H2, 24H2, 25H2
Windows Server products with known issues
- Windows Server 2023
- Windows Server 2025
Product Overview
Below is a breakdown of affected Windows versions and reported vulnerability counts.
Windows 11:
Windows 11 version 24H2
- Dozens of vulnerabilities fixed
- Includes remote code execution, privilege escalation, spoofing, and information disclosure flaws
Windows 11 version 25H2
- Same vulnerability scope as 24H2
- No critical vulnerabilities specific to this release alone
Windows 11 version 23H2 (Enterprise & Education)
- Still supported through enterprise servicing channels
- Receives cumulative security updates only
Windows 10
Windows 10 (Extended Security Updates only)
- Applies only to systems enrolled in ESU
- No feature updates
- General support ended in October 2025
Windows Server
- Windows Server 2016
- Windows Server 2019
- Windows Server 2022
- Windows Server 2023
- Windows Server 2025
All supported server versions received January security updates. While no critical vulnerabilities were publicly disclosed for server products, several important vulnerabilities were addressed.
Windows Security Updates
Windows 11 version 24H2 and 25H2
Support page: KB5074109
Updates and improvements:
- Security fixes for multiple remote code execution and elevation of privilege vulnerabilities
- Improvements to system stability and reliability
- Servicing changes related to Secure Boot and virtualization-based security
Windows 11 version 23H2 (Enterprise & Education)
Support page: KB5073455
Updates and improvements:
- Security fixes and quality improvements
- Includes changes related to Secure Boot certificates
Known issue:
- Systems with Secure Launch enabled may fail to shut down or enter sleep mode
- Devices may restart instead
Workaround:
Use a command prompt and run:
shutdown /s /t 0
Microsoft currently has no workaround for sleep mode.
Windows 10 (ESU)
Support page: KB5073724
- Security-only update
- Available exclusively to ESU-enrolled systems
- Removes outdated modem drivers as part of servicing
Windows Server Updates
- Windows Server 2025: KB5073379
- Windows Server 2023: KB5073450
Security updates only, with no feature changes.
Servicing Stack and Quality Updates
- KB5077800 — Servicing Stack Update (released January 17, 2026)
- Improves update installation reliability for older Windows builds
Microsoft Office Security Updates
On January 13, 2026, Microsoft released security updates for Office and server components.
Office updates include:
- Excel 2016 — KB5002831
- Office 2016 — KB5002826
- Word 2016 — KB5002829
SharePoint Server:
- SharePoint Server Subscription Edition — KB5002822
- SharePoint Server 2019 — KB5002825
- SharePoint Server 2016 — KB5002828
Language packs received corresponding updates.
Known Issues After Installing January Updates
Remote Desktop / Azure Virtual Desktop / Windows 365
Post-installation of the January updates, some users have reported:
- Credential prompt failures
- Authentication issues in Azure Virtual Desktop and Windows 365
- Problems primarily affect the new Windows App
Workarounds:
- Use the classic Remote Desktop client
- Use the web-based RDP client
Microsoft has acknowledged the issue and is actively investigating.
Windows 11 23H2 Shutdown and Sleep Issues
- Affects devices with Secure Launch enabled
- Prevents normal shutdown and sleep behavior
- Documented in Windows Release Health
Microsoft has released out-of-band fixes for some affected systems as of January 18, 2026.
How to Install the January 2026 Updates Immediately
While security updates are rolled out automatically, manual installation is also an option.
- Open the Start menu
- Type Windows Update and open it
- Select Check for updates
- Choose Download & install all
Recommendation:
Create a full system backup before installing updates, particularly on production systems.
Direct Update Downloads
Windows 11
- KB5074109 — Cumulative Update for Windows 11 24H2 / 25H2
- KB5073455 — Windows 11 23H2 (Enterprise & Education)
Windows 10 (ESU)
- KB5073724 — January 2026 ESU update