In its latest security update, Microsoft has released patches addressing 84 vulnerabilities, part of the September 2025 Patch Tuesday. Among the fixes are two zero-day vulnerabilities and eight marked as critical, with the remaining classified at varying levels of severity. The updates are crucial for reinforcing the security of Windows, Extended Security Updates, and Microsoft Office, which collectively earned significant patches this cycle.
Zero-Day Vulnerabilities in the Spotlight
Two zero-day vulnerabilities have been publicly disclosed but not actively exploited. The first, CVE-2025-55234, involves an elevation-of-privilege issue in the Windows SMB Server with a high CVSS score of 8.8. Without safeguards like SMB Server Signing or Extended Protection for Authentication, this flaw allows for potential relay attacks. Meanwhile, CVE-2024-21907 threatens systems through Newtonsoft.Json, creating a denial-of-service risk that disrupts applications by leveraging specifically crafted data.
Highlighting Critical Vulnerabilities
Critical vulnerabilities predominantly feature in Windows components and Microsoft Office. Notably, CVE-2025-54918 highlights an elevation-of-privilege weakness in NTLM, capable of elevating a user's privileges to SYSTEM remotely and with minimal complexity. CVE-2025-54910, targeting Microsoft Office, exposes systems to remote code execution attacks via heap-based buffer overflow, even when viewed through the Preview Pane.
Additional critical vulnerabilities such as CVE-2025-55228 and CVE-2025-53800 pertain to the Windows Graphics Component, allowing potential hypervisor escapes through privilege escalation or code execution. The new remote code execution flaw CVE-2025-49717 poses risks within Hyper-V, signalling attention to virtualized environments. Meanwhile, CVE-2025-53799, related to the Windows Imaging Component, highlights information disclosure risks, necessitating caution with unverified files.
Strategic Protection and Mitigation
Organizations must stay vigilant to unpatchable issues, building solid response plans to mitigate the vulnerabilities when immediate fixes aren't possible. Regular review and adaptation of patching strategies are essential for maintaining robust security frameworks. Vital to these endeavors is awareness of Microsoft's support timelines to ensure ongoing protection and timely upgrades. Utilizing tools like CrowdStrike’s Patch Tuesday dashboard can enhance operational understanding of system vulnerabilities and strengthen defenses.
The Common Vulnerability Scoring System (CVSS) remains a pivotal element in categorizing vulnerabilities by severity, assisting enterprises in appropriately prioritizing remediation measures. As businesses navigate the evolving threat landscape, these updates should be integrated into broader security initiatives to effectively protect infrastructures from emerging threats.
