CVE-2026-46570 in ntfs-3g
Summary
by MITRE • 10/07/2026
In NTFS-3G before 2026.7.7, a heap buffer overflow exists in ntfs_index_walk_down() 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 reading the special crafted file metadata.
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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_index_walk_down function found in the index.c source file. The root cause of this vulnerability lies in insufficient boundary checks when processing metadata structures within NTFS filesystem images. When an attacker crafts a malicious NTFS image containing specially designed file metadata, they can exploit this logic error to write data beyond the allocated bounds of heap memory buffers used by the library during index traversal operations.
From a technical perspective, the ntfs_index_walk_down function is responsible for navigating through B-tree indexes in the NTFS filesystem structure. During this process, it allocates temporary buffers on the heap to store intermediate results or metadata entries. The flaw arises because the code fails to validate that the size of incoming data from the crafted image does not exceed the capacity of these pre-allocated buffers. Consequently, when processing a maliciously constructed index entry with oversized fields, the function writes past the end of the buffer into adjacent memory regions on the heap. This out-of-bounds write corrupts heap metadata or potentially overwrites other objects stored in close proximity within the same allocation zone.
The operational impact of this vulnerability is severe due to its potential for remote code execution and privilege escalation. Since ntfs-3g is frequently invoked with root privileges, particularly when mounting NTFS partitions on Linux systems without native kernel support, an attacker who can trick a privileged user or system service into opening the malicious image gains significant leverage. By carefully crafting the heap overflow payload, it is possible to overwrite function pointers, return addresses, or other control data within the process memory space. This allows for arbitrary code execution in the context of the root user, effectively granting full administrative control over the affected system. The attack vector typically involves social engineering or automated exploitation where a victim mounts an untrusted NTFS volume, such as one provided via USB drive or network share.
This vulnerability aligns with CWE-122, which describes heap-based buffer overflow conditions resulting from improper bounds checking during memory allocation and usage. Furthermore, the exploitation technique maps to MITRE ATT&CK techniques related to privilege escalation through binary vulnerabilities, specifically leveraging local code execution to gain higher privileges. The lack of input validation on filesystem metadata is a common pattern in legacy or community-maintained file system drivers where performance optimizations sometimes bypass rigorous security checks against malformed inputs.
Mitigation strategies primarily involve upgrading the libntfs-3g library to version 2026.7.7 or later, which includes patches for this specific heap overflow condition. System administrators should ensure that automatic updates are enabled for filesystem utilities on all endpoints and servers relying on NTFS support. In environments where immediate patching is not feasible, restricting the ability of unprivileged users to mount arbitrary NTFS volumes can reduce the attack surface. Additionally, employing sandboxed execution contexts or mandatory access control policies like SELinux or AppArmor can limit the impact if an exploit attempt occurs by preventing the ntfs-3g binary from performing sensitive system calls even if code execution is achieved. Regular auditing of mounted filesystems and monitoring for unusual process behavior associated with mount operations also provides a layer of defense against such exploitation attempts.