Windows April 2025 Security Update Released: Patch Tuesday Brings Kerberos Fixes and More

This Tuesday, April 8th, Microsoft released its regular monthly security updates for Windows as part of the "Patch Tuesday" schedule. Keeping your system updated is crucial for protecting your computer from security threats, and this month's release includes important fixes, most notably for a vulnerability in the Kerberos authentication system.

What's Included in the April 2025 Update?

Like most Patch Tuesday releases, the primary focus of the April 2025 update is on security. It addresses vulnerabilities found in various components of the Windows operating system. Installing this update helps protect your PC against potential exploits and malware that target these weaknesses.

The update is available for all currently supported versions of Windows (such as Windows 11 and supported versions of Windows 10). Microsoft noted that the update for Windows 10 2015 LTSB would arrive slightly later.

Highlight: Kerberos Authentication Vulnerability Fix (CVE-2025-26647)

One of the most significant fixes included in this month's update addresses a security vulnerability related to Kerberos authentication (identified as CVE-2025-26647). Kerberos is a critical component used for authenticating users and services, especially within network environments like those using Windows Domain Controllers.

Microsoft is rolling out the protection for this vulnerability in phases:

• Phase 1 (Started April 8, 2025): Audit Mode. In this initial phase, the system will log events related to the vulnerability but won't actively block potentially affected authentication attempts by default. This allows administrators time to identify and update systems.
• Phase 2 (Starts July 8, 2025): Enforcement Mode. From this date onwards, the protection will be enforced by default, potentially blocking authentication attempts vulnerable to the exploit unless systems are properly configured.

For users in managed environments (like businesses or schools using Windows domains), IT administrators will need to ensure all Domain Controllers are updated with the April 2025 patch and may need to adjust specific settings to ensure full protection before the enforcement phase begins in July. For most home users, simply installing the update is the key step.

Other Security Fixes

Beyond the specific Kerberos fix, the April 2025 security update includes patches for numerous other vulnerabilities across the Windows ecosystem. These patches cover various components, potentially including the Windows Kernel, Secure Boot, graphics components, and other core services. Keeping these up-to-date is essential for overall system security.

How to Get the Update

For most users, the April 2025 security update should download and install automatically via Windows Update. You can manually check for updates:

1. Go to Settings (you can press Windows key + I).
2. Navigate to "Update & Security" (Windows 10) or "Windows Update" (Windows 11).
3. Click "Check for updates".

If the update is available, it will begin downloading. Remember that installing security updates usually requires restarting your computer, so be sure to save your work before initiating the restart.

A Note on WSUS Driver Synchronization

In related news mainly relevant for IT administrators in larger organizations, Microsoft announced on April 7th that it has postponed the planned deprecation (discontinuation) of driver synchronization through Windows Server Update Services (WSUS). This doesn't directly impact most home users but reverses a previously announced plan affecting some enterprise update management processes.

Conclusion: Update Promptly!

Installing the latest security updates is one of the most important things you can do to keep your Windows PC safe. The April 2025 update addresses known vulnerabilities, including the significant Kerberos issue. I strongly recommend checking Windows Update and installing this update as soon as possible.