Exploited Windows Zero-Day Resolved in April Patch Tuesday: What You Need to Know
In the dynamic landscape of cybersecurity, March has delivered a critical reminder for IT administrators: staying proactive is essential. With April’s Patch Tuesday, Microsoft addressed an alarming Windows zero-day vulnerability under active exploitation, marking it as the critical patch of the month. As an IT professional, understanding the nuances of this patch, along with additional vulnerabilities requiring manual intervention, is paramount to safeguarding your systems.
Critical Vulnerabilities of April Patch Tuesday
Microsoft rolled out patches for an impressive 121 vulnerabilities this April, with 11 rated as critical and the remainder classified as important. The overwhelming majority—90 vulnerabilities—exposed weaknesses in the Windows operating system, while 20 flaws were found in Microsoft Office.
Addressing the Windows Zero-Day Threat
The standout vulnerability this month is CVE-2025-29824, a significant Windows Common Log File System Driver elevation-of-privilege flaw rated important with a CVSS score of 7.8. This security gap affects most Windows Server and desktop systems. However, patches for Windows 10 x64-based and 32-bit systems have yet to be released.
An attacker, having local access—whether physically or through a remote access tool—can exploit this vulnerability using merely a standard user account. Chris Goettl, Vice President of Product Management for Security Products at Ivanti, highlighted the serious implications: “Should attackers successfully exploit this, they will gain full system privileges, rendering Windows systems highly vulnerable this month.”
Furthermore, Microsoft noted that the ransomware group Storm-2460 has been actively sweeping through organizations in the U.S., Venezuela, Spain, and Saudi Arabia. By exploiting such vulnerabilities, these attackers can firmly position themselves behind system-level controls before deploying malware.
Other Vulnerabilities Requiring Attention
While the zero-day is urgent, three additional vulnerabilities require IT administrators’ attention for manual mitigation.
1. Elevated Privileges with Kerberos
The first is CVE-2025-26647, a Windows Kerberos elevation-of-privilege vulnerability rated important with a CVSS score of 8.1—limited to Windows Server systems. This flaw allows attackers to escalate privileges by improperly validating input. Microsoft warns that even after applying the April updates, Windows domain controllers may still be vulnerable until crucial registry settings are manually enabled.
Goettl emphasized the need for caution, stating, “While the update is pushed out, it is not activated by default, requiring additional administrative actions to ensure security.”
2. Information Disclosure in NTFS and ReFS
Next, we address CVE-2025-21197, a Windows New Technology File System (NTFS) information disclosure vulnerability rated important with a CVSS score of 6.5. Patches for Windows 10 systems are not yet available, and the fix is disabled by default to mitigate potential application compatibility risks. Administrators must enable this fix via a registry key to enhance access checks on NTFS and Resilient File System (ReFS) volumes, preventing unauthorized users from viewing sensitive file paths.
3. The Future of Driver Support
In a notable shift, Microsoft has decided to delay the termination of driver update synchronization to Windows Server Update Services (WSUS), originally planned for April 18. This decision comes in response to customer feedback regarding disconnected device scenarios, emphasizing Microsoft’s commitment to supporting its users.
Looking Ahead
While this month’s patching efforts have addressed some of the most pressing vulnerabilities, IT administrators should remain vigilant. The ongoing developments underline the importance of regular updates and manual verifications in fortifying your defenses against ever-evolving threats.
As you navigate these updates, consider exploring alternative management strategies like Microsoft Intune and Windows Autopatch to maintain optimal security and compliance.
For further insights and detailed guides on patch management, visit TechTarget’s resources.
Stay informed, stay secure, and fortify your systems against the challenges that lie ahead.
