KB5079420 — March 2026 Hotpatch Security Update for Windows 11

Overview

KB5079420 is a critical security hotpatch update released on March 10, 2026, for Windows 11 systems. This update addresses multiple high-priority security vulnerabilities across various Windows subsystems and delivers fixes to Build 26200.7979 for Windows 11 Version 25H2 and Build 26100.7979 for Windows 11 Version 24H2. As a hotpatch update, KB5079420 applies security fixes without requiring system restart, minimizing disruption to business operations.

Security Vulnerabilities Addressed

This hotpatch update resolves several critical security vulnerabilities that could potentially compromise system security:

Kernel-Mode Driver Vulnerabilities

The update addresses elevation of privilege vulnerabilities in Windows kernel-mode drivers that could allow local attackers to gain administrative privileges. These vulnerabilities affect driver validation mechanisms and memory protection systems within the Windows kernel.

Network Stack Remote Code Execution

Critical remote code execution vulnerabilities in the Windows networking subsystem have been patched. These vulnerabilities could be exploited through specially crafted network packets to execute arbitrary code on target systems.

Graphics Subsystem Information Disclosure

Information disclosure vulnerabilities in Windows graphics processing components have been resolved. These issues could allow unauthorized access to sensitive memory contents through graphics driver interfaces.

Authentication Security Enhancements

The update strengthens Windows authentication mechanisms by addressing potential bypass vulnerabilities in credential validation processes and implementing enhanced cryptographic protections.

Affected Systems

KB5079420 applies to the following Windows 11 configurations:

Hotpatch Technology

Microsoft's hotpatch technology enables the delivery of critical security updates without requiring system restarts. This technology works by:

• Modifying running code in memory without affecting system stability
• Applying security patches to active processes and system components
• Maintaining system uptime while delivering critical security fixes
• Reducing maintenance windows for enterprise environments

Installation and Deployment

Automatic Installation

Windows 11 systems configured for automatic updates will receive KB5079420 automatically through Windows Update. The hotpatch installation process is transparent to users and occurs in the background.

Enterprise Deployment

Enterprise environments can deploy this update through:

• Windows Server Update Services (WSUS): Centralized deployment for domain-joined systems
• Microsoft Intune: Cloud-based update management for modern workplace scenarios
• Microsoft Update Catalog: Manual download for offline deployment
• System Center Configuration Manager: Traditional enterprise update deployment

Verification Commands

To verify successful installation of KB5079420, use the following PowerShell command:

Get-HotFix -Id KB5079420

To check the current OS build number:

[System.Environment]::OSVersion.Version

Security Impact and Recommendations

Organizations should prioritize the installation of KB5079420 due to the critical nature of the security vulnerabilities addressed. The hotpatch delivery mechanism ensures minimal disruption while providing immediate security protection.

Risk Assessment

Systems not updated with KB5079420 remain vulnerable to:

• Local privilege escalation attacks
• Remote code execution through network exploitation
• Information disclosure through graphics subsystem vulnerabilities
• Authentication bypass attempts

Compliance Considerations

This update may be required for compliance with security frameworks such as:

• NIST Cybersecurity Framework
• ISO 27001 security standards
• Industry-specific security requirements
• Government security mandates

Support and Additional Resources

For technical support related to KB5079420, contact Microsoft Support through official channels. Enterprise customers with Premier or Unified Support contracts can access dedicated support resources for update deployment assistance.