CVE-2026-46569 in ntfs-3g
Summary
by MITRE • 10/07/2026
In NTFS-3G before 2026.7.7, a heap buffer overflow exists in ntfs_ib_copy_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 extending a directory, e.g., by creating a file.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified as CVE 2024-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_copy_tail function found in the index.c source file. The root cause of this vulnerability lies in insufficient bounds checking when processing NTFS directory structures during extension operations. When an attacker crafts a malicious NTFS image containing specifically formatted and oversized directory entries, they can exploit this logic error to write data beyond the allocated heap memory boundaries. This type of flaw is classically categorized under CWE-122, which denotes a heap-based buffer overflow, indicating that the application fails to properly validate input size relative to the destination buffer capacity during runtime execution.
The operational impact of this vulnerability is severe due to its potential for remote code execution and privilege escalation. The ntfs-3g utility is frequently executed with root privileges because it requires elevated permissions to mount filesystems and manage disk structures on Linux-based systems. Consequently, when a user mounts or interacts with the malicious NTFS image using the vulnerable version of ntfs-3g, the heap corruption occurs within a SUID-root binary context. This environment allows an attacker who successfully exploits the buffer overflow to overwrite critical memory structures such as function pointers or return addresses on the stack and heap. By carefully crafting the payload embedded in the malformed directory entry, an attacker can achieve arbitrary code execution with root-level privileges, effectively gaining full control over the host system.
From a threat intelligence perspective, this vulnerability aligns with ATT&CK technique T1203, which covers Exploitation for Client Execution, and potentially T1059 if used to execute scripts or commands within an automated context. The attack vector typically involves tricking a user into mounting the malicious image via graphical file managers like Nautilus or Dolphin, which often utilize ntfs-3g as their backend driver for NTFS support. This makes the vulnerability particularly dangerous in desktop environments where users routinely interact with external storage devices without deep technical scrutiny of the underlying filesystem integrity checks. The lack of strict validation on directory entry sizes during the copy tail operation provides a reliable foothold for attackers to bypass standard security controls that rely on memory safety assumptions.
Mitigation strategies must focus primarily on immediate software updates and defensive configuration measures. Organizations and individual users should upgrade libntfs-3g to version 2026.7.7 or later, where the bounds checking logic in ntfs_ib_copy_tail has been corrected to prevent out-of-bounds writes. In environments where updating is not immediately feasible, administrators can mitigate risk by disabling automatic mounting of NTFS volumes through desktop environment settings or configuring mount options that restrict user access to untrusted filesystems. Additionally, employing memory protection mechanisms such as Address Space Layout Randomization (ASLR) and Stack Canaries can reduce the likelihood of successful exploitation, although these are compensating controls rather than definitive fixes. Security teams should also audit systems for any instances where ntfs-3g is invoked with elevated privileges to assess exposure levels and prioritize patching efforts accordingly.