Microsoft's September 2025 Patch Tuesday release has unfolded with a broad collection of updates, addressing 80 vulnerabilities across its software suite. Of these, eight are designated as Critical, intensifying the focus on prompt security measures. Despite the volume and severity, none of the vulnerabilities have been reported as zero-day exploits in active circulation.
Priority on Privilege Escalation
Tenable's Satnam Narang emphasized the significant presence of privilege escalation vulnerabilities, constituting 47.5% of the month's disclosures. Within the lineup, there are also 22 remote code execution flaws, which pose a critical concern for potential unauthorized command executions. Other vulnerabilities disclosed encompass 14 information disclosure issues and three denial-of-service weaknesses.
One of the crucial highlights from this month’s Patch Tuesday is a publicly known vulnerability in Windows SMB, cataloged as CVE-2025-55234 with a CVSS score of 8.8. Microsoft alerts that under specific configurations, SMB Server could fall victim to relay attacks resulting in privilege elevation, pushing stakeholders to consider recommended hardening solutions.
Enhancing SMB Security
With this update, Microsoft introduces enhanced auditing capabilities for detecting SMB client compatibility issues with SMB Server signing. Rapid7's Adam Barnett underscores the value these options offer administrators in identifying potential mismatches that could impede hardening status. Insights on this issue have been extended with input from Mike Walters, president of Action, who stresses that lack of validation in established SMB sessions can pave the way for man-in-the-middle attacks dedicating credential compromise and unauthorized lateral movements.
Azure and HPC Pack Vulnerabilities
The gravest vulnerability addressed bears a CVSS rating of 10.0, found in Azure Networking. Although deemed critical, it remains noteworthy that this flaw manifests on the cloud-side, sparing customers from active remediation steps. Another significant fix pertains to a remote code execution threat within the Microsoft High Performance Compute Pack, marked at a CVSS score of 9.8.
Tackling NTLM and Newtonsoft.Json Flaws
In a scenario where access to NTLM hashes could be leveraged, an elevation of privilege vulnerability (CVSS 8.8) underscores the risks of attackers attaining SYSTEM privileges. In discussions led by researchers such as Kev Breen from Immersive, the threat becomes more tangible when examining vulnerabilities like those connected to malformed network packets.
Moreover, attention has also focused on a vulnerability in the widely-utilized Newtonsoft.Json component by SQL Server, with a CVSS score of 7.5. Left unpatched, this flaw could precipitate a denial-of-service condition, negatively impacting database availability.
BitLocker Enhancements
The September update revisits issues revolving around Windows BitLocker. Following previous patches in July, two additional privilege escalation vulnerabilities have been addressed. These support Microsoft's recommendations framed by STORM researchers like Netanel Ben Simon, who encourages strengthening protection by enabling TPM+PIN for pre-boot authentication and secure versioning control.
The presence of a technique labeled BitLockMove demonstrates Microsoft's continuous scrutiny into sophisticated attack vectors. This method manipulates registry keys through Windows Management Instrumentation (WMI) to compromise BitLocker COM objects remotely, effectively executing code under the context of an interactive user.
This comprehensive approach in the latest Patch Tuesday updates not only fortifies Microsoft's own software against emergent threats, but also coincides with parallel efforts from other vendors striving to seal vulnerabilities in their respective platforms.
