CVE-2023-26607: Linux Kernel Buffer Overflow Vulnerability

CVE-2023-26607 Overview

CVE-2023-26607 is an out-of-bounds read vulnerability in the Linux kernel's NTFS file system implementation. The flaw exists in the ntfs_attr_find function located in fs/ntfs/attrib.c, which can be exploited by a local attacker with low privileges to read sensitive kernel memory or cause a denial of service condition.

Critical Impact

Local attackers can exploit this vulnerability to access sensitive kernel memory contents or crash the system, potentially exposing confidential information or disrupting system availability.

Affected Products

• Linux Kernel versions prior to patched releases
• NetApp HCI Baseboard Management Controller (H300s, H410c, H410s, H500s, H700s models)

Discovery Timeline

• 2023-02-26 - CVE-2023-26607 published to NVD
• 2025-05-05 - Last updated in NVD database

Technical Details for CVE-2023-26607

Vulnerability Analysis

This vulnerability is classified as CWE-125 (Out-of-bounds Read), occurring within the NTFS attribute parsing code in the Linux kernel. The ntfs_attr_find function in fs/ntfs/attrib.c fails to properly validate memory boundaries when processing NTFS file system attributes. When the kernel attempts to read attribute data from a maliciously crafted or corrupted NTFS volume, it can read beyond the allocated buffer boundaries.

The vulnerability requires local access to exploit, meaning an attacker would need to mount a specially crafted NTFS filesystem or manipulate an existing NTFS volume on the target system. Successful exploitation could allow the attacker to leak sensitive kernel memory contents, which may include cryptographic keys, credentials, or other privileged data. Additionally, the out-of-bounds read could trigger a kernel panic, resulting in system unavailability.

Root Cause

The root cause of this vulnerability lies in insufficient bounds checking within the ntfs_attr_find function. When iterating through NTFS attribute records, the function does not adequately verify that attribute offsets and lengths stay within the bounds of the allocated memory buffer. This oversight allows reads to extend beyond the intended memory region when processing malformed attribute data structures.

Attack Vector

An attacker with local access and low privileges can exploit this vulnerability by mounting a malicious NTFS filesystem image containing specially crafted attribute records. The attack vector is local, requiring the attacker to have the ability to mount filesystems or access an existing NTFS volume on the target system. The vulnerability can be triggered when the kernel's NTFS driver parses the malformed attributes during mount operations or file access, leading to out-of-bounds memory reads that can expose kernel memory or cause system crashes.

Detection Methods for CVE-2023-26607

Indicators of Compromise

• Unexpected kernel crashes or panics related to NTFS filesystem operations
• Suspicious NTFS filesystem mount attempts from unprivileged users
• Kernel log entries (dmesg) showing memory access violations in fs/ntfs/attrib.c
• Unusual filesystem mount activity targeting removable media or network shares

Detection Strategies

• Monitor kernel logs for NTFS-related errors and memory access violations using tools like auditd or journalctl
• Implement file integrity monitoring on systems with NTFS volumes mounted
• Deploy endpoint detection solutions capable of identifying kernel memory access anomalies
• Alert on unexpected NTFS mount operations, particularly from non-administrative users

Monitoring Recommendations

• Enable kernel audit logging for mount system calls and filesystem operations
• Configure SentinelOne agents to monitor for kernel-level anomalies and memory corruption indicators
• Review system logs regularly for NTFS driver errors or unexpected behavior
• Implement alerting for kernel oops or panic events that reference NTFS code paths

How to Mitigate CVE-2023-26607

Immediate Actions Required

• Update the Linux kernel to a patched version that addresses this vulnerability
• Restrict NTFS filesystem mount privileges to trusted administrators only
• Disable NTFS kernel module loading if NTFS support is not required (blacklist ntfs in modprobe configuration)
• Audit systems for untrusted NTFS volumes and remove or unmount as appropriate

Patch Information

The Linux kernel developers have addressed this vulnerability in commit 36a4d82dddbbd421d2b8e79e1cab68c8126d5075. Organizations should apply kernel updates from their distribution vendors that include this fix. For detailed patch information, refer to the Linux Kernel Commit and the SUSE Bug Report #1208703. NetApp customers should review the NetApp Security Advisory NTAP-20230316-0010 for guidance on affected HCI Baseboard Management Controller products.

Workarounds

• Blacklist the NTFS kernel module to prevent loading: add blacklist ntfs to /etc/modprobe.d/blacklist.conf
• Restrict mount privileges using fstab options and removing users from disk-related groups
• Use user-space NTFS implementations (ntfs-3g) instead of kernel NTFS driver where possible
• Implement mandatory access control policies (SELinux/AppArmor) to restrict filesystem mounting capabilities

# Disable NTFS kernel module loading
echo "blacklist ntfs" >> /etc/modprobe.d/blacklist-ntfs.conf
echo "install ntfs /bin/false" >> /etc/modprobe.d/blacklist-ntfs.conf

# Update module dependencies
depmod -a

# Verify module is blacklisted
modprobe -n -v ntfs