KB5075899 — March 2026 Cumulative Update for Windows 10 and Windows 11

Overview

KB5075899 is a comprehensive cumulative update released on March 11, 2026, for Windows 10 22H2 and Windows 11 23H2/24H2 systems. This update addresses critical security vulnerabilities, resolves system stability issues, and implements performance improvements based on user feedback and telemetry data collected by Microsoft.

The update is classified as Important and includes security fixes for two critical vulnerabilities: CVE-2026-0847 (Microsoft Edge WebView2 remote code execution) and CVE-2026-0851 (Windows kernel privilege escalation). Additionally, it resolves several high-impact issues affecting Windows Search functionality, File Explorer performance, and Windows Update reliability.

Security Vulnerabilities Addressed

This cumulative update patches multiple security vulnerabilities that could potentially compromise system security:

CVE-2026-0847 - Microsoft Edge WebView2 Remote Code Execution

A critical vulnerability in the Microsoft Edge WebView2 runtime could allow an attacker to execute arbitrary code in the context of the current user. This vulnerability affects applications that embed WebView2 components, including Microsoft Teams, Office applications, and numerous third-party applications.

CVSS Score: 8.8 (High)
Attack Vector: Network
User Interaction: Required
Impact: Complete compromise of application security context

CVE-2026-0851 - Windows Kernel Elevation of Privilege

A privilege escalation vulnerability in the Windows kernel could allow an authenticated user to gain SYSTEM-level privileges. The vulnerability exists due to improper validation of user-mode callback parameters in kernel-mode drivers.

CVSS Score: 7.8 (High)
Attack Vector: Local
User Interaction: None
Impact: Complete system compromise

System Compatibility

The following table outlines the compatibility matrix for KB5075899:

Performance Improvements

Beyond security fixes, KB5075899 introduces several performance optimizations:

File Explorer Enhancements

The update includes significant improvements to File Explorer's file enumeration algorithms, particularly when working with directories containing large numbers of files. Microsoft's testing shows up to 40% improvement in folder navigation speed for directories with more than 1,000 files.

Windows Search Reliability

A critical fix addresses the Windows Search service failure that occurred when systems resumed from sleep or hibernation. This issue affected Start menu search, File Explorer search, and Cortana functionality, causing these features to return no results until the search service was manually restarted.

Memory Usage Optimization

The update includes optimizations to reduce memory consumption during thumbnail generation and file indexing operations, resulting in improved system responsiveness on systems with limited RAM.

Enterprise Considerations

IT administrators should be aware of the following considerations when deploying KB5075899:

Group Policy Impact

This update does not introduce new Group Policy settings but may affect existing policies related to Windows Search and Windows Update configurations. Test deployments in a controlled environment before broad rollout.

Application Compatibility

While extensive compatibility testing has been performed, some legacy applications may require updates to work properly with the new WebView2 runtime. Maintain an inventory of applications using WebView2 and coordinate with vendors as needed.

Network Infrastructure

The update includes changes to network stack components that may affect VPN connectivity and network printer access. Ensure network infrastructure and security appliances are compatible with the updated networking components.

Installation Best Practices

To ensure successful deployment of KB5075899, follow these best practices:

1. Backup Critical Data: Create system backups before installing the update, particularly for production systems
2. Test in Staging Environment: Deploy to a representative test environment before production rollout
3. Schedule Maintenance Windows: Plan installation during scheduled maintenance windows as a system restart is required
4. Monitor System Performance: Monitor system performance for 24-48 hours after installation to identify any issues
5. Update Documentation: Update system documentation to reflect the new build numbers and installed components

Rollback Procedures

If issues occur after installing KB5075899, the update can be removed using the following methods:

Settings App Method

1. Open Settings > Update & Security > Windows Update
2. Click View update history
3. Click Uninstall updates
4. Select KB5075899 and click Uninstall
5. Restart the system when prompted

Command Line Method

For automated or remote uninstallation, use the following command with administrative privileges:

wusa /uninstall /kb:5075899 /quiet /norestart