09-07-2025
High-Severity Windows Flaw Revealed by Security Expert
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Positive Technologies has revealed a high-severity vulnerability affecting 37 desktop and server Windows operating systems. The flaw impacts Windows 11, Windows 10, Server 2025, Server 2022, and Server 2019 across various versions and architectures.
The vulnerability, identified as CVE-2025-49689, was discovered by Sergey Tarasov, Specialist at the Positive Technologies Expert Security Center. It affects the NTFS file system driver and was assigned a CVSS 3.1 severity score of 7.8.
The flaw could have enabled privilege escalation if a user opened a malicious virtual hard disk (VHD). This would allow attackers to bypass Windows security and gain full control of the system.
Microsoft was notified under responsible disclosure protocols and released patches in July 2025.
• Over 1.5 million devices are reportedly exposed
• U.S. and China account for the largest number of affected systems
StatCounter data shows Windows 11's market share rose from below 30% in 2024 to over 43% by May 2025.
Tarasov explained that attackers often use VHD files in phishing campaigns. Many users treat these files like ordinary archives, increasing the risk of exploitation.
Positive Technologies recommends users install the latest Windows updates. If updates cannot be applied, users should only open VHD files from trusted sources.
The company also advises deploying its tools, including MaxPatrol VM and MaxPatrol EDR, to detect and prevent similar threats.
In 2024, Tarasov helped address another vulnerability, CVE-2024-43629, affecting Windows 10, 11, and Server editions. In 2017, the PT Expert Security Center collaborated with Microsoft to resolve CVE-2017-0263.
