CVE-2026-46571 in ntfs-3g
Summary
by MITRE • 10/07/2026
In NTFS-3G before 2026.7.7, a out-of-bounds read exists in ntfs_fix_file_name() in libntfs-3g/reparse.c that allows an attacker to read possibly confidential information in ntfs-3g process memory by crafting a malicious NTFS image. The out-of-bounds read is triggered by a readlink on a corrupted file.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified in versions of NTFS-3G prior to 2026.7.7 represents a critical security flaw within the library's handling of reparse points, specifically located in the ntfs_fix_file_name function found in libntfs-3g/reparse.c. This component is responsible for processing and validating file names associated with NTFS reparse tags, which are metadata structures used to store additional information about files or directories, such as symbolic links or mount points. The core technical flaw is an out-of-bounds read condition that occurs when the library processes a maliciously crafted NTFS image containing corrupted or malformed reparse data. When an application invokes the readlink system call on a file associated with this compromised structure, the function fails to adequately validate buffer boundaries before attempting to access memory locations beyond the allocated limits of the internal buffers. This lack of rigorous bounds checking allows the program to retrieve and potentially expose arbitrary bytes from its own process memory space that lie outside the intended data structures.
From an operational perspective, this vulnerability poses a significant risk of information disclosure. An attacker who can trick a victim into opening or processing a malicious NTFS image file can trigger the out-of-bounds read through standard filesystem operations like readlink. The immediate consequence is the leakage of sensitive data residing in the memory of the ntfs-3g process, which could include cryptographic keys, authentication tokens, private user files, or other confidential information previously loaded into memory by the application utilizing NTFS-3G for storage management. This type of attack does not require code execution privileges but relies on social engineering or supply chain compromise to deliver the malicious image file, making it a viable vector for targeted data exfiltration in environments where external drives or network shares formatted with NTFS are commonly accessed.
In terms of industry standard classifications, this vulnerability aligns closely with CWE-125, which describes Out-of-bounds Read vulnerabilities involving access to memory beyond the intended buffer boundaries. The exploitation technique falls under ATT&CK tactic T1005, specifically subtechnique T1005.004 for Data from Local System Memory, as it involves reading sensitive information directly from the application's memory space rather than extracting files from disk storage. Furthermore, because the vulnerability is triggered via a standard POSIX filesystem operation (readlink), it highlights the risks associated with parsing untrusted file system metadata without strict validation of structural integrity and length constraints.
Mitigation strategies primarily involve upgrading to NTFS-3G version 2026.7.7 or later, where this specific bounds checking issue has been resolved by developers implementing stricter validation logic within ntfs_fix_file_name. For environments unable to immediately patch the software, defensive measures include restricting access to untrusted external storage devices and disabling automatic mounting of NTFS volumes from unknown sources. Additionally, applications utilizing NTFS-3G should implement sandboxing or privilege separation principles to limit the potential impact if a memory leak occurs, ensuring that sensitive data is not stored in long-lived processes with high privileges unless absolutely necessary for operation. Regular security audits focusing on file system parsing libraries are also recommended to identify similar patterns of insufficient input validation across other components handling complex metadata structures.