CVE-2026-46570: 
CBL Mariner vulnerability analysis and mitigation

CVE-2026-46570 is a heap-based buffer overflow vulnerability in NTFS-3G's ntfs_index_walk_down() function (located in libntfs-3g/index.c) that allows a local attacker to corrupt heap memory in the SUID-root ntfs-3g binary by crafting a malicious NTFS image. All versions of NTFS-3G prior to 2026.7.7 are affected, including the previously stable release 2026.2.25. The vulnerability was disclosed on July 15, 2026, when the patched version 2026.7.7 was released. It carries a CVSS v3.1 base score of 8.1 (High) (GitHub Advisory, Red Hat Bugzilla).

The root cause is a heap-based buffer overflow (CWE-122) combined with an out-of-bounds write (CWE-787) in the ntfs_index_walk_down() function within libntfs-3g/index.c. The overflow is triggered when the library processes specially crafted file metadata in a malicious NTFS image — specifically, corrupt or maliciously crafted index data that causes the code to descend to an out-of-bounds tree depth, overwriting adjacent heap memory. Because ntfs-3g runs as a SUID-root binary, the corrupted heap memory is in a privileged process context. Exploitation requires high attack complexity (e.g., crafting a precise NTFS image), but no privileges or user interaction are needed beyond the ability to present the malicious image to the system (GitHub Advisory, Red Hat Bugzilla). The vulnerability was reported by Alexandro Calo' from Nozomi Networks Labs (reference: NN-2026-0090) (GitHub Advisory).

Successful exploitation allows a local, unauthenticated user to corrupt heap memory within the SUID-root ntfs-3g process, potentially achieving arbitrary code execution with root privileges — constituting a full privilege escalation. The impact spans all three security dimensions: high confidentiality (access to sensitive system data), high integrity (unauthorized modification of system data), and high availability (potential system crash or disruption). Because the vulnerable binary runs as root, a successful exploit could grant an attacker complete control over the affected host, enabling lateral movement, persistence, or data exfiltration (GitHub Advisory, Red Hat Bugzilla).

As of the time of reporting, there is no public proof-of-concept exploit and no evidence of in-the-wild exploitation (Feedly). The EPSS score is approximately 0.128%, reflecting a low near-term exploitation probability. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. Exploitation is rated as non-automatable due to the high attack complexity required to craft a precisely malformed NTFS image (GitHub Advisory).

1. Craft a malicious NTFS image: Using NTFS image manipulation tools or custom code, create an NTFS filesystem image with specially crafted index metadata that encodes an out-of-bounds tree depth value in the index structures processed by ntfs_index_walk_down().
2. Deliver the image to the target: Place the malicious NTFS image file on the target system (e.g., via a USB drive, network share, or downloaded file) accessible to a local unprivileged user.
3. Trigger mounting or access: Cause the SUID-root ntfs-3g binary to process the malicious image — for example, by mounting it (ntfs-3g malicious.img /mnt/point) or using an ntfs-3g tool that reads the image's index metadata.
4. Trigger the overflow: When ntfs-3g parses the crafted index data and calls ntfs_index_walk_down(), the malformed tree depth causes a heap buffer overflow, overwriting adjacent heap memory in the root-privileged process.
5. Achieve code execution: With careful heap layout manipulation (heap grooming), redirect execution flow to attacker-controlled code, achieving arbitrary code execution as root (GitHub Advisory).

• Process: Unexpected child processes (e.g., /bin/sh, bash, python) spawned by the ntfs-3g process; ntfs-3g process crashing with segmentation faults or heap corruption errors.
• Logs: System logs (/var/log/syslog, dmesg) showing segfaults or heap corruption messages from the ntfs-3g process; audit logs recording unexpected SUID binary executions by unprivileged users.
• File System: Unexpected NTFS image files (.img, .ntfs) in user-accessible directories; new files or scripts created in privileged directories (e.g., /etc/cron.d/, /root/) shortly after ntfs-3g invocation.
• Network: Outbound connections from the host to unknown external IPs following ntfs-3g execution (indicative of post-exploitation activity such as reverse shells).

The primary remediation is to upgrade NTFS-3G to version 2026.7.7 or later, which contains the fix for CVE-2026-46570. Backport patches are also available for older versions: ntfs-3g_2022.10.3-cve_2026-04_6.patch (for 2022.10.3) and ntfs-3g_2026.2.25-cve_2026-04_6.patch (for 2026.2.25) (GitHub Advisory). No configuration-based workarounds are known. As interim risk reduction measures, administrators should restrict access to mounting NTFS filesystems, avoid mounting NTFS images from untrusted sources, and consider disabling the SUID bit on the ntfs-3g binary if FUSE-based NTFS mounting by unprivileged users is not required. Major Linux distributions including Ubuntu (USN-8554-1), SUSE (SUSE-SU-2026:3213-1), Debian, and Gentoo have issued updated packages (Ubuntu Advisory, SUSE Advisory).

The vulnerability was credited to Alexandro Calo' from Nozomi Networks Labs (report reference NN-2026-0090), indicating professional security research involvement (GitHub Advisory). The July 2026 NTFS-3G 2026.7.7 release addressed eight CVEs simultaneously, drawing attention from the Linux security community and prompting rapid patch adoption across major distributions. The vulnerability was also noted in the context of Microsoft's October 2026 Patch Tuesday coverage, reflecting its cross-platform relevance given NTFS-3G's use in Linux environments interacting with Windows filesystems (BleepingComputer).