Microsoft’s latest Patch Tuesday rollout addresses 78 vulnerabilities, including five 0-day exploits confirmed to be actively exploited in the wild.

For security engineers and CISOs, this update is particularly important—not only because of the volume of fixes, but because it highlights several recurring pain points in Microsoft’s kernel and core subsystem components.

Below is a list of the actively exploited zero-day vulnerabilities disclosed this month:

• CVE-2025-30397 (CVSS score: 7.5) – Scripting Engine Memory Corruption

• CVE-2025-30400 (CVSS score: 7.8) – Desktop Window Manager (DWM) Core Library Elevation of Privilege (Important)

• CVE-2025-32701 (CVSS score: 7.8) – Windows Common Log File System (CLFS) Driver Elevation of Privilege (Important)

• CVE-2025-32706 (CVSS score: 7.8) – Windows CLFS Driver Elevation of Privilege (Important)

• CVE-2025-32709 (CVSS score: 7.8) – Windows Ancillary Function Driver for WinSock Elevation of Privilege (Important)

Breakdown and Analysis of Key Vulnerabilities

CVE-2025-30397 is a memory corruption vulnerability in the scripting engine that can be triggered through malicious web content. This vulnerability enables arbitrary code execution in the context of the user and has been actively weaponized through phishing emails and compromised websites. Detection should focus on behavior-based triggers such as abnormal scripting activity from browser processes and suspicious use of Active Scripting in Office applications. Mitigation includes disabling Active Scripting where unnecessary, deploying attack surface reduction rules, and applying Microsoft’s patch immediately.

CVE-2025-30400 targets the Desktop Window Manager (DWM) Core Library and has been exploited for privilege escalation. The attack vector leverages UI subsystem weaknesses to bypass user access controls post-exploitation. Detection can be achieved by correlating unusual DWM process spawning with account privilege changes. Organizations should implement User Account Control (UAC) policies with strict auditing and consider isolating DWM execution where feasible on high-value systems.

CVE-2025-32701 and CVE-2025-32706 affect the Common Log File System (CLFS) driver. Both are exploited for elevation of privilege via kernel-level vulnerabilities. These attacks typically involve malformed log entries or memory manipulation through undocumented APIs. Detection is challenging but can be improved with kernel telemetry and monitoring for anomalous log write patterns or access to CLFS.sys. Mitigation strategies include applying the latest security patches, reducing local admin privileges, and enforcing strict driver signing policies.

CVE-2025-32709 affects the Ancillary Function Driver for WinSock, allowing attackers to escalate privileges by manipulating network stack behavior. Detection may require monitoring for suspicious use of Winsock APIs and non-standard communications initiated from non-network services. Enhanced logging on RPC and socket API usage can aid in identifying exploit attempts. Systems should be patched immediately, and legacy networking services audited for unnecessary exposure.

Conclusion

Microsoft’s May 2025 release is not just another routine patch cycle—it underscores the sustained targeting of core Windows components by advanced adversaries. Attackers are moving away from traditional malware and leaning heavily on kernel exploits and misused native components to achieve persistence and privilege escalation. As such, security teams must go beyond patch management and invest in deeper telemetry, advanced correlation rules, and endpoint hardening.

For organizations seeking to improve detection and response capabilities against these threats, Silent Breach offers a suite of solutions tailored to the modern threat landscape. Our red team engagements simulate real-world privilege escalation and kernel-level attack chains to expose gaps in EDR, SIEM, and identity controls. We provide tailored focused on components like CLFS, DWM, and Winsock, along with purple team workshops designed to refine response playbooks in live environments.

Whether you're looking to harden your infrastructure or validate your defensive posture, Silent Breach has the expertise to help you stay ahead of zero-day exploitation.

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