CVE-2026-80869
Received Received - Intake

Buffer Overflow in Linux Kernel NTFS Driver

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: ntfs: bound the attribute-list entry in ntfs_read_inode_mount() The $MFT attribute-list walk in ntfs_read_inode_mount() validates each entry only with "(u8 *)al_entry + 6 > al_end" and "(u8 *)al_entry + le16_to_cpu(al_entry->length) > al_end", but then reads al_entry->lowest_vcn (an __le64 at offset 8) and al_entry->mft_reference (offset 16) -- fields beyond the 6 bytes proven in range. al_entry->length is attacker-controlled and only required non-zero, so a short entry (e.g. length 8) placed at the tail passes both checks while the lowest_vcn / mft_reference reads fall past al_end. al_end is ni->attr_list + attr_list_size (the on-disk size); the buffer is kvzalloc(round_up(attr_list_size, SECTOR_SIZE)), so the sector rounding usually absorbs the over-read -- but when attr_list_size is a multiple of SECTOR_SIZE there is no slack and a crafted $MFT attribute list produces an out-of-bounds read at mount time. Validate the entry with ntfs_attr_list_entry_is_valid() (added in patch 1/3) before dereferencing it, matching the bound the other attribute-list walks now use. The validator already requires the length to cover the fixed header, which makes the separate "!al_entry->length" check redundant, so drop it too.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-05
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-80869
EUVD
EUVD-2026-71499

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux_kernel ntfs *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability in the NTFS file system driver. It involves an out-of-bounds read during the mounting of an NTFS filesystem. The issue occurs when parsing the Master File Table (MFT) attribute list, where a crafted entry with a short length can pass validation checks but still cause the driver to read beyond the allocated buffer. This happens because the validation logic only checks if the entry starts within bounds but does not ensure the entire entry, including fields like lowest_vcn and mft_reference, fits within the buffer.

Detection Guidance

This vulnerability is specific to the Linux kernel's NTFS implementation and can be detected by checking the kernel version for affected releases. Use 'uname -r' to check your kernel version and compare it against patched versions. Monitor kernel logs for NTFS mount errors during system boot or when accessing NTFS volumes.

Impact Analysis

This vulnerability could allow an attacker with local access to cause a denial of service (system crash) by mounting a maliciously crafted NTFS filesystem. If successful, it may lead to kernel memory corruption or system instability. However, exploitation requires the attacker to have the ability to create or modify NTFS filesystems and mount them on a vulnerable system.

Mitigation Strategies

Update the Linux kernel to a version containing the fix. Avoid mounting untrusted NTFS volumes until patched. If immediate patching is not possible, restrict access to systems with NTFS mounts or disable NTFS support if not required.

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