CVE-2025-32707 Overview
CVE-2025-32707 is an out-of-bounds read vulnerability in the Windows NTFS file system driver. The flaw allows a local, unauthenticated attacker to elevate privileges on affected systems after a user interacts with a crafted artifact. Microsoft published the advisory on May 13, 2025, covering multiple supported Windows client and server editions. The weakness is tracked under [CWE-125] (Out-of-bounds Read) and resides in kernel-mode file system code that parses NTFS metadata.
Critical Impact
Successful exploitation grants attackers SYSTEM-level privileges, enabling full compromise of confidentiality, integrity, and availability on the local host.
Affected Products
- Microsoft Windows 10 (versions 1507, 1607, 1809)
- Microsoft Windows Server 2008, 2008 R2, 2012, and 2012 R2
- Microsoft Windows Server 2016 and Windows Server 2019
Discovery Timeline
- 2025-05-13 - CVE-2025-32707 published to NVD with Microsoft security advisory
- 2025-05-19 - Last updated in NVD database
Technical Details for CVE-2025-32707
Vulnerability Analysis
The vulnerability stems from improper bounds checking in the NTFS driver when reading file system structures. NTFS parses metadata such as Master File Table (MFT) records, attribute headers, and index entries during normal file operations. When the driver processes a malformed structure, it reads memory beyond the intended buffer boundary. The condition is classified as [CWE-125] Out-of-bounds Read.
An attacker leverages this read primitive to disclose kernel memory contents or to trigger logic that leads to privilege escalation. Exploitation requires local access and user interaction, typically through mounting or opening a malicious NTFS volume such as a crafted VHD or VHDX file.
Root Cause
The driver fails to validate the size or offset of attributes within an NTFS structure before dereferencing them. Crafted on-disk metadata causes the kernel to read past the allocated buffer. The resulting memory disclosure exposes pointers and structures that defeat kernel address space layout randomization (KASLR), enabling reliable follow-on exploitation.
Attack Vector
The attack requires local access with no prior authentication but depends on user interaction. A common path involves delivering a malicious virtual hard disk file that the user mounts in Windows Explorer. Mounting parses the NTFS metadata in kernel context and triggers the out-of-bounds read. The vulnerability is not exploitable remotely over a network.
No public proof-of-concept or in-the-wild exploitation is currently documented. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2025-32707
Indicators of Compromise
- Unexpected mounting of .vhd or .vhdx files from user-writable locations such as Downloads or Temp directories.
- Kernel-mode crashes or bug checks referencing ntfs.sys shortly after disk image interaction.
- Creation of new SYSTEM-level processes following user-initiated mount operations on untrusted media.
Detection Strategies
- Monitor for process creation events where explorer.exe or vds.exe invokes mount operations on files originating from email attachments or web downloads.
- Alert on token manipulation or privilege assignment events (Windows Event ID 4672, 4673) immediately following NTFS volume mount activity.
- Inspect kernel crash dumps for faulting modules involving NTFS parsing routines.
Monitoring Recommendations
- Enable PowerShell and Sysmon logging to capture Mount-DiskImage cmdlet usage and virtual disk service activity.
- Forward kernel event logs and minidump telemetry to a centralized SIEM for correlation with user logon context.
- Baseline normal VHD/VHDX usage in the environment and flag deviations from administrative workflows.
How to Mitigate CVE-2025-32707
Immediate Actions Required
- Apply the May 2025 Microsoft security update referenced in the Microsoft Security Update Guide to all affected hosts.
- Prioritize patching on multi-user systems, file servers, and endpoints where users routinely handle external disk images.
- Audit endpoints running unsupported Windows versions and accelerate migration plans where patches are unavailable.
Patch Information
Microsoft released cumulative updates addressing CVE-2025-32707 on May 13, 2025. The fix corrects the bounds validation logic within the NTFS driver. Administrators should deploy the appropriate cumulative update for each Windows version through Windows Update, WSUS, or Microsoft Update Catalog. Refer to the vendor advisory at MSRC CVE-2025-32707 for KB numbers per build.
Workarounds
- Restrict mounting of untrusted disk image files by removing file association handlers for .vhd and .vhdx on standard user workstations.
- Use Group Policy or AppLocker to block execution of disk image mounting utilities for non-administrative users.
- Educate users to avoid opening virtual hard disk attachments received via email or downloaded from untrusted sources.
# Remove default mount handler for VHD/VHDX files via registry (run as administrator)
reg delete "HKCR\Windows.VhdFile\shell\Mount" /f
reg delete "HKCR\Windows.VhdxFile\shell\Mount" /f
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
