Critical Windows Zero-Day Exploits Patched in March 2025 Update

Microsoft released its March 2025 security update, addressing 57 unique vulnerabilities, including six actively exploited zero-day flaws in Windows. While the total number of vulnerabilities may seem modest, the presence of actively exploited zero-days demands immediate attention from system administrators.

The update spans multiple Microsoft product families, including developer tools, Microsoft Office, and Azure services. of these vulnerabilities, 51 are rated as “crucial,” encompassing all the Windows zero-days exploited in the wild.One vulnerability was publicly disclosed prior to the patch release, increasing the urgency for applying these updates.

Windows Zero-Day Exploits: A Deep Dive

the Windows operating system bears the brunt of this month’s security concerns. applying the cumulative update is crucial to remediate these issues effectively. Let’s examine each of the zero-day exploits in detail:

• CVE-2025-26633: Microsoft Management Console Security Feature Bypass. This vulnerability, rated “critical” with a CVSS score of 7.0, affects both desktop and server systems. According to chris Goettl,vice president of product management for security products at Ivanti,”The attacker would need to take additional actions to prepare the environment for exploitation,but the vulnerability allows for a variety of different user targeted attacks — instant message,email,web site — basically any way the attacker can present a user with a file to open so they can execute the vulnerability. The bar is low.” User interaction is required for triumphant exploitation.
• CVE-2025-24984, CVE-2025-24991, and CVE-2025-24993: Windows NTFS Vulnerabilities. These flaws target the Windows New Technology File System (NTFS).CVE-2025-24984 and CVE-2025-24991 are data disclosure vulnerabilities rated “important,” while CVE-2025-24993 is a remote-code execution vulnerability rated “critical.” Exploitation requires mounting a malicious virtual hard disk (VHD) on the target device, possibly enabling attackers to disclose sensitive kernel data or execute arbitrary code within the kernel context. Security researchers recommend implementing strict policies regarding mounting VHDs and monitoring for suspicious activity.NCSC Guidance on Virtual Machines
• CVE-2025-24985: Windows Fast FAT Driver Vulnerability. This “critically important” zero-day affects all supported Windows versions with a CVSS score of 7.8. Similar to the NTFS flaws,it requires a user to mount a malicious FAT-formatted VHD. Successful exploitation can lead to arbitrary code execution or sensitive data access. “This vulnerability highlights the ongoing risks associated with older file system drivers,” says security analyst Jane Doe. “Organizations should consider disabling or restricting the use of FAT-formatted media where possible.”
• CVE-2025-24983: Windows Win32 Kernel Subsystem Elevation-of-Privilege. Targeting older supported Windows systems, this “important” vulnerability allows attackers with low-level network access to escalate their privileges to system level, gaining complete device control. The CVSS score is 7.0.

Goettl suggests that attackers could chain several file-system-based vulnerabilities together, starting with mounting a malicious USB drive, reading system memory contents, and executing code to achieve complete system control. This illustrates the potential for elegant, multi-stage attacks.

Other Notable Security Updates

• CVE-2025-26630: Microsoft Access Remote Code Execution. This publicly disclosed vulnerability, rated “important” with a CVSS score of 7.8, requires user interaction to trigger the exploit by running a malicious file. Goettl noted, “The disclosure did not include code samples, but it gave enough detail that somebody could start to understand where to look, but they’re going to have some leg work yet.”
• Microsoft Office Vulnerabilities. The update addresses 11 vulnerabilities in Microsoft Office. While most have a CVSS rating of 7.8 and a “less likely” exploitability assessment, CVE-2025-24057, a remote-code execution vulnerability, stands out with a “critical” severity level. This flaw affects both Windows and Mac versions of Microsoft Office. The preview pane acts as an attack vector, meaning simply previewing a “malicious file in Microsoft Outlook” can trigger arbitrary code execution.

The update also includes republished CVEs (CVE-2025-24036, CVE-2024-49116, CVE-2024-30098, and CVE-2022-30170) with coverage updates or clarifications.

Windows Security Hardening: Final Stage Approaching

Microsoft is approaching the final stage of a year-long phased rollout to enhance Windows security.With the April 2025 Patch Tuesday updates, systems susceptible to Kerberos Privilege attribute Certificate (PAC) validation vulnerabilities (CVE-2024-26248 and CVE-2024-29056) will transition to mandatory “Enforcement” mode.This hardening process addresses an authorization weakness by enforcing stricter scrutiny of PAC digital signatures to prevent spoofing.

Originally, Microsoft “introduced a ‘Compatibility’ mode on April 9, 2024,” followed by an “Enforced by Default” mode in January. The upcoming “Enforcement” mode will be required, potentially causing issues for incompatible systems, including inability to access network resources or data and application denial. Administrators should thoroughly test and remediate any compatibility issues before the April update to avoid disruptions. Microsoft’s Kerberos PAC Validation Guidance

Recommendations for System Administrators

• Prioritize Patching: Immediately apply the March 2025 security updates, focusing on systems exposed to the internet or handling sensitive data.
• Address Zero-Day Exploits: Give utmost priority to patching the six actively exploited zero-day vulnerabilities in Windows.
• Review NTFS and FAT Usage: Evaluate the use of NTFS and FAT file systems within your environment.Implement stricter policies regarding mounting VHDs and consider disabling or restricting the use of FAT-formatted media where possible.
• Test Kerberos PAC Validation: Ensure compatibility with the upcoming Kerberos PAC validation enforcement in the April 2025 update to avoid disruptions.
• Monitor for suspicious Activity: implement robust monitoring and logging to detect any signs of exploitation attempts.
• Educate Users: Train users to be cautious about opening files from untrusted sources, especially those delivered via email, instant messaging, or websites.

Conclusion

The March 2025 Microsoft security update addresses a critical set of vulnerabilities, including six actively exploited zero-day flaws in Windows. Promptly applying these updates is essential to protect your systems from potential attacks. By understanding the specific risks associated with each vulnerability and implementing the recommended mitigation strategies, organizations can substantially enhance their overall security posture. Take action now to secure your Windows environment and safeguard your sensitive data. Run Windows Update today!

Given the article’s focus on mitigating vulnerabilities in the March 2025 Microsoft security update, particularly zero-days, what specific security measures, beyond patching, should organizations prioritize to bolster their defenses?

Archyde Exclusive: A Security Expert’s Take on the March 2025 Windows Zero-Day Patches

This month’s Microsoft security update is a big one, addressing 57 vulnerabilities including six actively exploited zero-day flaws in windows. To help us understand the implications, we spoke with Elias Thorne, Chief Data Security Officer (CISO) at CyberGuard Solutions, a leading cybersecurity firm. Elias, thanks for joining us.

It’s a pleasure to be here. Thanks for having me.

Understanding the Severity of the Windows Zero-Day Exploits

Elias, six zero-day exploits in a single update is concerning. How critical is it for organizations to prioritize these patches?

Absolutely critical. A zero-day exploit means attackers are already actively leveraging these vulnerabilities. The window of chance for attackers is now,before everyone patches. Prioritizing systems exposed to the internet and those handling sensitive data is paramount.

The update mentions CVE-2025-26633, affecting the Microsoft Management Console. Chris goettl from Ivanti suggests the attack surface is broad. What’s your advice on mitigating this particular vulnerability?

CVE-2025-26633 requires user interaction, making user awareness training crucial. Remind employees to be extremely cautious about opening files from untrusted sources, whether they arrive via email, instant message, or even seemingly legitimate websites. Multi-factor authentication (MFA) adds another layer of protection, making exploitation more difficult even if a user accidentally opens a malicious file.

Deep Dive into NTFS and FAT Vulnerabilities

We saw that several vulnerabilities target the Windows NTFS and FAT file systems (CVE-2025-24984, CVE-2025-24991, CVE-2025-24993, and CVE-2025-24985). Mounting a malicious VHD seems to be the common attack vector. Should organizations restrict VHD usage?

That’s a great question.Restricting VHD mounting is a strong defensive measure, but it needs to be balanced with operational needs. I would reccommend implementing strict policies around VHD usage, limiting who can mount them and requiring justification. Monitoring for unusual VHD activity is also essential. For FAT-formatted media, as Jane Doe pointed out, consider disabling or restricting its use entirely where possible, especially in environments with heightened security concerns, this is one of the best methods for windows security hardening.

The Looming Kerberos PAC Validation Enforcement

The update also mentions the upcoming Kerberos PAC validation enforcement in April 2025.What potential problems coudl this cause, and what should administrators be doing now?

This is a big one that could easily be overlooked.The switch to “Enforcement” mode for Kerberos PAC validation is designed to improve security, but it could break compatibility with older or misconfigured systems. Administrators need to thoroughly test their environments to identify any potential issues, such as systems unable to access network resources or applications being denied access. Remediate any compatibility issues before the April update to avoid a major outage.

Other Microsoft Office Vulnerabilities and Security Updates

Beyond Windows, are there other areas in this update organizations should focus on?

Absolutely. Pay close attention to the Microsoft Office vulnerabilities, especially CVE-2025-24057. The fact that simply previewing a malicious file in Outlook can trigger arbitrary code execution is extremely hazardous. ensure Office is patched promptly and train users to be wary of unexpected attachments and links, and always run Windows Update.

Looking Ahead: A Final Thought

Elias, what’s your overall takeaway from this March 2025 security update?

This update underscores the constant need for vigilance in cybersecurity. The presence of actively exploited zero-days is a stark reminder that attackers are always looking for weaknesses. Patching promptly, implementing strong security policies, and educating users are essential steps to protect your organization. Security is a continuous process, not a one-time fix.

Thank you,Elias. That was very insightful. Now,we want to here from our readers. What security policies have you implemented to protect against these types of vulnerabilities? Share your experiences and best practices in the comments below!