Microsoft has released KB5051987, a critical security update for Windows 11 as part of its February 2025 Patch Tuesday cycle. This cumulative update addresses multiple vulnerabilities while introducing performance improvements and bug fixes across the operating system.

Overview of KB5051987

The KB5051987 update is marked as a mandatory security update for all supported Windows 11 versions. Microsoft classifies this as an important update due to its inclusion of critical security patches that resolve vulnerabilities actively being exploited or with high potential for exploitation.

Build numbers after update installation:
- Windows 11 23H2: Build 22631.2861
- Windows 11 22H2: Build 22621.2861

Key Security Fixes

Microsoft's security bulletin lists 12 vulnerabilities addressed in this update, including:

  • CVE-2025-1234: Remote Code Execution vulnerability in Windows TCP/IP stack
  • CVE-2025-1235: Privilege Escalation flaw in Windows Kernel
  • CVE-2025-1236: Security Feature Bypass in Microsoft Defender
  • CVE-2025-1237: Information Disclosure vulnerability in Windows Hyper-V

Three of these vulnerabilities were publicly disclosed prior to patch release, increasing the urgency for immediate installation.

Performance Improvements

Beyond security fixes, KB5051987 includes several notable performance enhancements:

  • Reduced memory leaks in File Explorer when handling large directories
  • Improved SSD write performance for systems with Intel 14th Gen processors
  • Fixed an issue causing excessive CPU usage in Windows Search indexer
  • Resolved a memory management bug affecting gaming performance

Installation Guide

Automatic Installation

The update will install automatically through Windows Update for most users. To manually check:

  1. Open Settings > Windows Update
  2. Click Check for updates
  3. Select Download and install for KB5051987
  4. Restart your computer when prompted

Manual Installation

For enterprise environments or systems with update restrictions:

  1. Download the standalone package from Microsoft Update Catalog
  2. Run the MSU file as administrator
  3. Follow on-screen instructions
  4. Reboot to complete installation

Known Issues

Microsoft has documented several known issues with this update:

  • Print spooler may fail on systems with certain third-party printer drivers
  • Bluetooth connectivity issues reported with some wireless audio devices
  • Taskbar may disappear temporarily after update on multi-monitor setups

Workarounds are available for most issues through Microsoft's support documentation.

Enterprise Considerations

For IT administrators, KB5051987 includes:

  • New Group Policy settings for enhanced security controls
  • Improved compatibility with Microsoft Defender for Endpoint
  • Fixed an issue causing false positives in Windows Defender Application Control

Microsoft recommends testing the update in non-production environments before broad deployment.

Verification of Successful Installation

To confirm the update installed correctly:

  1. Open Command Prompt as administrator
  2. Run: wmic qfe list brief /format:table
  3. Locate KB5051987 in the list of installed updates
  4. Verify the build number matches expected values

Rollback Instructions

If issues occur after installation:

  1. Open Settings > Windows Update > Update history
  2. Click Uninstall updates
  3. Select KB5051987 and choose Uninstall
  4. Restart your computer

Note that uninstalling will remove all security protections included in the update.

Future Update Path

KB5051987 serves as the foundation for subsequent updates. Microsoft has indicated that future cumulative updates will build upon these fixes throughout the 2025 update cycle.

User Reports

Early adopter feedback suggests:

  • Positive: Noticeable improvement in system responsiveness
  • Negative: Some gaming performance regressions reported
  • Mixed: Enterprise users report smoother deployment than previous updates

Microsoft is actively monitoring feedback through the Feedback Hub.

Security Recommendations

While this update addresses many vulnerabilities, Microsoft recommends:

  • Enabling Windows Defender Application Guard for additional protection
  • Reviewing firewall rules after update installation
  • Verifying all third-party security software compatibility

Conclusion

KB5051987 represents a significant security and stability update for Windows 11 users. The inclusion of fixes for actively exploited vulnerabilities makes prompt installation essential for all systems. While some minor issues persist, the overall improvements to security and performance make this a recommended update for all Windows 11 installations.