KB5075999 — February 2026 Security Update for Windows 10 Version 1607 and Windows Server 2016

Overview

KB5075999 is a comprehensive security update released on February 10, 2026, for Windows 10 Version 1607 and Windows Server 2016 systems. This update addresses multiple critical and important security vulnerabilities across various Windows components, updating the operating system build to 14393.8868. The update is part of Microsoft's regular monthly security update cycle and includes fixes for vulnerabilities that could potentially allow attackers to execute arbitrary code, elevate privileges, or compromise system security.

Security Vulnerabilities Addressed

This update resolves several categories of security vulnerabilities that affect core Windows components:

Kernel-Mode Driver Vulnerabilities

Multiple vulnerabilities in Windows kernel-mode drivers, particularly in the win32k.sys component, have been addressed. These vulnerabilities could allow local attackers to gain elevated privileges through exploitation of buffer overflow conditions and use-after-free scenarios in graphics subsystem calls. The fixes include enhanced input validation routines and improved memory protection mechanisms.

Network Protocol Stack Issues

Critical vulnerabilities in the TCP/IP stack and related network protocols have been resolved. These issues could potentially allow remote attackers to execute arbitrary code by sending specially crafted network packets. The update includes comprehensive improvements to packet validation routines and enhanced memory management in network driver components, specifically targeting malformed packet handling in both IPv4 and IPv6 implementations.

Graphics Component Security

The update addresses memory corruption vulnerabilities in Graphics Device Interface (GDI) and DirectWrite components. These vulnerabilities could be exploited through maliciously crafted fonts or graphics files to achieve code execution. The fixes include improved bounds checking in gdi32.dll and DWrite.dll, along with enhanced validation of graphics rendering operations.

Authentication System Enhancements

Significant improvements have been made to Windows Authentication mechanisms, including NTLM and Kerberos protocols. The update strengthens these systems against authentication bypass attacks and credential theft scenarios. Enhanced token validation, improved encryption algorithms, and strengthened authentication handshake procedures help prevent man-in-the-middle attacks and unauthorized access attempts.

Message Queuing Service Security

Vulnerabilities in the Microsoft Message Queuing (MSMQ) service that could allow remote code execution have been patched. The fixes include enhanced message validation, improved access control mechanisms, and strengthened inter-process communication security to prevent exploitation through maliciously crafted messages.

Affected Systems

This update applies to the following operating systems and architectures:

Installation Requirements

Before installing KB5075999, ensure your system meets the following requirements:

• Available Disk Space: Minimum 2 GB free space on the system drive
• System Architecture: Compatible with 32-bit and x64-based systems
• Network Connectivity: Required for automatic installation through Windows Update
• Administrative Privileges: Installation requires administrator rights

Installation Process

The update can be installed through multiple methods depending on your environment:

Automatic Installation

For most users, KB5075999 will be automatically downloaded and installed through Windows Update. The system will prompt for a restart when installation is complete.

Manual Installation

Enterprise administrators can download the standalone package from the Microsoft Update Catalog for manual deployment. The update can also be deployed through Windows Server Update Services (WSUS) or System Center Configuration Manager (SCCM) for centralized management.

Command Line Installation

For automated deployment scenarios, the update can be installed using the following command:

wusa.exe windows10.0-kb5075999-x64.msu /quiet /norestart

Post-Installation Verification

After successful installation, verify the update has been applied by checking the system build number:

Get-ComputerInfo | Select-Object WindowsVersion, WindowsBuildLabEx

The output should show build number 14393.8868 or higher. You can also verify the installation through:

Get-HotFix -Id KB5075999

Impact Assessment

This security update provides critical protection against multiple attack vectors while maintaining system stability and performance. The fixes are designed to be transparent to end users and applications, with minimal impact on system functionality. However, organizations should test the update in non-production environments before widespread deployment to ensure compatibility with their specific configurations and applications.