CVE-2025-24991 Overview
CVE-2025-24991 is an out-of-bounds read vulnerability in the Windows NTFS file system driver that allows an authorized attacker to disclose sensitive information locally. This vulnerability affects a wide range of Microsoft Windows operating systems, including both client and server editions spanning from Windows Server 2008 through the latest Windows 11 and Windows Server 2025 releases.
The flaw exists in how the NTFS driver processes certain file system operations, enabling attackers to read memory contents beyond intended boundaries. When successfully exploited, this vulnerability can expose sensitive kernel memory data, potentially revealing credentials, encryption keys, or other confidential information stored in system memory.
Critical Impact
This vulnerability is actively exploited in the wild and has been added to CISA's Known Exploited Vulnerabilities (KEV) catalog. Organizations should prioritize patching immediately.
Affected Products
- Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
- Microsoft Windows 11 (versions 22H2, 23H2, 24H2)
- Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, 2022 23H2, 2025
Discovery Timeline
- March 11, 2025 - CVE-2025-24991 published to NVD
- October 27, 2025 - Last updated in NVD database
Technical Details for CVE-2025-24991
Vulnerability Analysis
This vulnerability is classified as CWE-125 (Out-of-bounds Read), which occurs when the NTFS driver reads data from a location outside the bounds of the intended buffer. In the context of file system operations, this type of vulnerability can be particularly dangerous as the NTFS driver operates at the kernel level with elevated privileges.
The out-of-bounds read condition can be triggered when the NTFS driver processes malformed file system metadata or specially crafted file operations. Because NTFS is the primary file system for Windows, the attack surface is extensive, affecting virtually all Windows systems that mount NTFS volumes.
The vulnerability requires local access and user interaction, meaning an attacker would typically need to convince a user to mount a malicious disk image or access a specially crafted file on a compromised NTFS volume.
Root Cause
The root cause of CVE-2025-24991 lies in improper bounds checking within the Windows NTFS driver during file system operations. When processing certain NTFS structures, the driver fails to properly validate the length or offset of data being read, allowing read operations to extend beyond allocated buffer boundaries into adjacent kernel memory regions.
This type of vulnerability typically occurs when:
- Buffer length calculations contain arithmetic errors
- Offset validation is missing or incomplete
- Trusted metadata from the file system is used without proper sanitization
Attack Vector
The attack requires local access to the target system. An attacker must craft a malicious NTFS volume or file that, when processed by the vulnerable driver, triggers the out-of-bounds read condition. The exploitation scenario typically involves:
- Creating a malicious NTFS disk image or storage device with specially crafted metadata
- Social engineering a user to mount the malicious volume (e.g., via USB drive or downloaded disk image)
- The NTFS driver processes the malformed structures, reading memory beyond intended boundaries
- Sensitive kernel memory contents are disclosed to the attacker
Given that this vulnerability is actively exploited in the wild (as confirmed by its CISA KEV listing), threat actors have developed practical exploitation techniques that security teams should be aware of.
Detection Methods for CVE-2025-24991
Indicators of Compromise
- Unusual NTFS driver behavior or unexpected system crashes related to ntfs.sys
- Mounting of unfamiliar or suspicious disk images (.vhd, .vhdx, .iso files)
- Unauthorized USB storage device connections
- Abnormal memory access patterns in kernel-mode operations
Detection Strategies
- Monitor for mounting of disk images from untrusted sources or email attachments
- Deploy endpoint detection and response (EDR) solutions capable of detecting kernel-level memory access anomalies
- Enable Windows Defender Exploit Guard and Attack Surface Reduction (ASR) rules
- Implement behavioral analysis to detect exploitation attempts targeting the NTFS driver
Monitoring Recommendations
- Review Windows Event Logs for disk mount events and NTFS-related errors
- Configure SentinelOne agents to detect suspicious file system operations and kernel memory access patterns
- Monitor for unexpected removable media connections, particularly in sensitive environments
- Establish baseline behavior for file system operations to identify anomalies
How to Mitigate CVE-2025-24991
Immediate Actions Required
- Apply the latest Windows security updates from Microsoft immediately
- Block or restrict mounting of external disk images from untrusted sources
- Disable AutoRun/AutoPlay features to prevent automatic execution when connecting storage devices
- Review and restrict USB device policies in enterprise environments
Patch Information
Microsoft has released security updates addressing this vulnerability. Organizations should apply patches as documented in the Microsoft Update Guide for CVE-2025-24991. Given the active exploitation status and CISA KEV listing, patching should be treated as an emergency priority.
SentinelOne customers are protected through behavioral AI and kernel-level monitoring capabilities that can detect exploitation attempts targeting this vulnerability. Ensure SentinelOne agents are updated to the latest version for optimal protection.
Workarounds
- Restrict user permissions for mounting disk images to trusted administrators only
- Implement application control policies to block execution of files from mounted external volumes
- Disable automatic mounting of removable storage devices via Group Policy
- Consider using SentinelOne's device control features to manage USB and external storage access
# Disable AutoRun/AutoPlay via Registry
reg add "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer" /v NoDriveTypeAutoRun /t REG_DWORD /d 255 /f
# Disable AutoPlay via Group Policy command
reg add "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Explorer" /v NoAutorun /t REG_DWORD /d 1 /f
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
