BaseFortify

Publication date: 2026-01-13

Last updated on: 2026-03-25

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: ntfs: set dummy blocksize to read boot_block when mounting When mounting, sb->s_blocksize is used to read the boot_block without being defined or validated. Set a dummy blocksize before attempting to read the boot_block. The issue can be triggered with the following syz reproducer: mkdirat(0xffffffffffffff9c, &(0x7f0000000080)='./file1\x00', 0x0) r4 = openat$nullb(0xffffffffffffff9c, &(0x7f0000000040), 0x121403, 0x0) ioctl$FS_IOC_SETFLAGS(r4, 0x40081271, &(0x7f0000000980)=0x4000) mount(&(0x7f0000000140)=@nullb, &(0x7f0000000040)='./cgroup\x00', &(0x7f0000000000)='ntfs3\x00', 0x2208004, 0x0) syz_clone(0x88200200, 0x0, 0x0, 0x0, 0x0, 0x0) Here, the ioctl sets the bdev block size to 16384. During mount, get_tree_bdev_flags() calls sb_set_blocksize(sb, block_size(bdev)), but since block_size(bdev) > PAGE_SIZE, sb_set_blocksize() leaves sb->s_blocksize at zero. Later, ntfs_init_from_boot() attempts to read the boot_block while sb->s_blocksize is still zero, which triggers the bug. [[email protected]: changed comment style, added return value handling]

CVSS Scores

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Meta Information

Published

2026-01-13

Last Modified

2026-03-25

Generated

2026-07-06

AI Q&A

2026-01-14

EPSS Evaluated

2026-07-04

NVD

CVE-2025-71067

EUVD

EUVD-2026-2258

Affected Vendors & Products

Vendor	Product	Version / Range
paragon_software	ntfs	-

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability occurs in the Linux kernel's NTFS mounting process. When mounting an NTFS filesystem, the block size used to read the boot block (sb->s_blocksize) is not properly defined or validated and can remain zero. Specifically, if the block size of the block device is larger than the system page size, the block size is not set correctly, leaving sb->s_blocksize at zero. Later, when the kernel tries to read the boot block using this zero block size, it triggers the bug. The fix involves setting a dummy block size before attempting to read the boot block to prevent this issue.

Impact Analysis

The vulnerability can cause improper handling of the NTFS filesystem mount process, potentially leading to kernel errors or crashes when reading the boot block due to an invalid block size. This could result in system instability or denial of service when mounting NTFS filesystems under certain conditions.

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