CVE-2026-46572 in ntfs-3g
Summary
by MITRE • 10/07/2026
In NTFS-3G before 2026.7.7, a heap buffer overflow exists in ntfs_ib_cut_tail() in libntfs-3g/index.c that allows an attacker to corrupt heap memory in the SUID-root ntfs-3g binary by crafting a malicious NTFS image. The overflow is triggered by creating a file in a specially crafted directory.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified as CVE-2026-XXXX represents a critical security flaw within the libntfs-3g library, specifically affecting versions prior to 2026.7.7. This issue manifests as a heap buffer overflow located in the ntfs_ib_cut_tail function found in index.c of the NTFS-3G source code. The root cause lies in improper boundary checking during the processing of NTFS file system structures, particularly when handling directory entries and inode manipulation operations. An attacker can exploit this flaw by constructing a malicious NTFS image that contains specially crafted directory metadata designed to trigger an out-of-bounds write operation within the heap memory space allocated for index buffer management.
From a technical perspective, the ntfs_ib_cut_tail function is responsible for managing the tail end of index buffers in NTFS directories. When processing these structures, the library fails to adequately validate the size parameters derived from the malicious image data. This lack of validation allows an attacker to supply values that exceed the allocated buffer limits, resulting in a heap overflow. The exploitation vector involves creating a file within this specially crafted directory structure on the mounted volume. As the operating system or user-space application interacts with these files through the NTFS-3G driver, the malformed data triggers the overflow condition, leading to memory corruption beyond the intended boundaries of the allocated buffer.
The operational impact of this vulnerability is severe due to its potential for privilege escalation and arbitrary code execution. Since ntfs-3g often runs with root privileges or SUID permissions in many Linux distributions to allow non-root users access to NTFS partitions, a successful exploitation can lead to full system compromise. By corrupting heap memory adjacent to the overflowed buffer, an attacker may overwrite function pointers, return addresses, or other critical control data structures within the process address space. This corruption enables the execution of arbitrary code with elevated privileges, effectively bypassing standard user-level security restrictions and granting the attacker complete control over the affected system.
This vulnerability aligns closely with CWE-122, which describes a heap-based buffer overflow where memory is allocated on the heap rather than the stack, making exploitation techniques more complex but potentially more impactful due to the larger address space available for manipulation. Furthermore, from an offensive security perspective such as MITRE ATT&CK, this flaw facilitates initial access and privilege escalation tactics. The ability to execute arbitrary code via a mounted volume image allows attackers to introduce malware or establish persistence mechanisms without requiring direct network exposure or physical console access if removable media is involved.
Mitigation strategies primarily involve updating the NTFS-3G software to version 2026.7.7 or later, where this boundary check issue has been resolved by developers implementing stricter validation of input parameters before performing buffer operations. In environments where immediate patching is not feasible, administrators should restrict access to untrusted NTFS volumes and avoid mounting images from unknown sources. Additionally, employing security mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) can help mitigate the impact of heap corruption by making it more difficult for attackers to reliably predict memory layouts or execute injected code. Regular auditing of mounted file systems and monitoring for unusual process behavior associated with ntfs-3g processes are also recommended defensive measures to detect potential exploitation attempts in real-time.