Microsoft April 2025 Patch Tuesday: Critical Vulnerabilities and a Zero-Day Exploit
Comprehensive Guide to Microsoft’s April 2025 Security Patches – Zero-Day, Zero Delay
Microsoft April 2025 Patch Tuesday: Critical Vulnerabilities and a Zero-Day Exploit
Microsoft’s April 2025 Patch Tuesday has arrived with a substantial security update addressing over 120 vulnerabilities, including an actively exploited zero-day vulnerability in the Windows Common Log File System (CLFS). This month’s update is particularly significant, more than doubling the number of fixes compared to last month.
Zero-Day Vulnerability: CVE-2025-29824
Microsoft Threat Intelligence Center (MSTIC) and Microsoft Security Response Center (MSRC) have discovered post-compromise exploitation of a zero-day elevation of privilege vulnerability in the Windows Common Log File System (CLFS) against a small number of targets. The targets include organizations in the information technology (IT) and real estate sectors of the United States, the financial sector in Venezuela, a Spanish software company, and the retail sector in Saudi Arabia.
CVE-2025-29824 is a user-after-free vulnerability in the Windows Common Log File System (CLFS) that can be – and is being – exploited by attackers to elevate their privileges to SYSTEM on previously compromised Windows machines.
Microsoft says the RansomEXX ransomware gang has been exploiting this high-severity zero-day flaw in the Windows Common Log File System to gain SYSTEM privileges on victims’ systems. The vulnerability, tracked as CVE-2025-29824, was patched during this month’s Patch Tuesday and was only exploited in a limited number of attacks.
CLFS is no stranger to Patch Tuesday – since 2022, Microsoft has patched 32 CLFS vulnerabilities, averaging 10 each year, with six exploited in the wild. The last CLFS zero-day flaw exploited in the wild was patched in December 2024.
The exploit follows a common pattern where attackers first compromise systems using the PipeMagic backdoor malware, which then deploys the CVE-2025-29824 exploit to gain elevated privileges, enabling the deployment of ransomware.
Notable Security Patches
Beyond the zero-day vulnerability, this month’s Patch Tuesday includes several critical remote code execution (RCE) vulnerabilities:
This Patch Tuesday also fixes eleven “Critical” vulnerabilities, all remote code execution vulnerabilities.
Key vulnerabilities addressed include:
- Windows LDAP Server vulnerabilities (CVE-2025-26663 and CVE-2025-26670): Critical remote code execution flaws affecting LDAP servers and clients.
- Remote Desktop Services vulnerabilities (CVE-2025-27480 and CVE-2025-27482): These critical RCE vulnerabilities could allow attackers to execute code without user interaction if they connect to a system with the Remote Desktop Gateway role.
- Windows Hyper-V vulnerability (CVE-2025-27491): A critical RCE vulnerability in Windows virtualization technology.
- Windows TCP/IP vulnerability (CVE-2025-26686): A critical remote code execution vulnerability in the networking stack.
- Multiple Microsoft Office vulnerabilities: Several critical vulnerabilities affecting Microsoft Office applications, including Excel and Word.
Windows 11 24H2’s April 2025 update also fixes an issue where Windows update might create a non-functional boot menu entry. This happens when trying to install a Windows update, but it stops working and accidentally creates an entry in the boot menu.
Microsoft has planned to end support for driver update synchronization to Windows Server Update Services (WSUS) servers, but changed its mind. For the time being, “WSUS will continue to synchronize driver updates from the Windows Update service and import them from the Microsoft Update Catalog.”
File Explorer Bug Fix
Patch Tuesday began rolling out on Tuesday morning, and it will finally patch most of the major annoying issues in Windows 11 24H2. This includes a fix for a bug where the menu (three dots) will open in the opposite direction, causing it to appear outside the screen when the File Explorer’s window is maximized.
This fix addresses a particularly frustrating UI issue that has plagued Windows 11 24H2 users, though Microsoft notes the fix is being rolled out in stages, so some users may not see it immediately after updating.
The Importance of Timely Patching
With the RansomEXX ransomware gang actively exploiting the CLFS zero-day vulnerability, organizations must prioritize applying these security updates. Ransomware threat actors specifically target elevation of privilege vulnerabilities as they enable the attackers to escalate initial access into privileged access, which can then be used for widespread deployment of ransomware.
Microsoft highly recommends that organizations prioritize applying security updates for elevation of privilege vulnerabilities to add a layer of defense against ransomware attacks if threat actors are able to gain an initial foothold.
How CinchOps Helps Secure Your Business
Staying on top of critical security patches like those released in April’s Patch Tuesday can be challenging for IT teams. CinchOps simplifies this process with automated patching for Windows, macOS, and Linux systems, ensuring your organization’s digital infrastructure remains secure against emerging threats.
Our AI-enabled sentiment analysis evaluates patch stability before deployment, reducing the risk of patches causing operational disruptions. By leveraging this technology, CinchOps ensures critical security updates are applied promptly while minimizing potential negative impacts on your business operations.
With CinchOps, organizations can:
- Automatically track and deploy critical security patches across multiple operating systems
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- Maintain a strong security posture against evolving threats like the RansomEXX ransomware group
Discover more about our enterprise-grade and business protecting cybersecurity services on our Cybersecurity page.
Don’t let critical vulnerabilities like CVE-2025-29824 put your organization at risk. Contact CinchOps today to learn how our automated patching solutions can strengthen your security posture while reducing IT management overhead.
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