---
id: CVE-2026-90117
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ntfs: validate usa_ofs before preserving the update sequence number

  When ntfs_mft_record_alloc() reuses a free mft record it reads the old
  update sequence number strai…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ntfs: validate usa_ofs before preserving the update sequence number

  When ntfs_mft_record_alloc() reuses a free mft record it reads the old
  update sequence number strai…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 495e90fa334828d4119061e2726af51d0a0fb4ed <
    ea5a3c30710710c1dc5e483d3313309ec2e868f7
  - >-
    Linux >= 495e90fa334828d4119061e2726af51d0a0fb4ed <
    81684340963da2e898eabb8c1e274433d9375bc6
  - Linux 7.1
published: '2026-09-17'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T17:17:03.857'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90117'
references:
  - url: 'https://git.kernel.org/stable/c/81684340963da2e898eabb8c1e274433d9375bc6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ea5a3c30710710c1dc5e483d3313309ec2e868f7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-17T16:21:47.885Z'
epss: 0.00198
epssPercentile: 0.08477
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

ntfs: validate usa_ofs before preserving the update sequence number

When ntfs_mft_record_alloc() reuses a free mft record it reads the old
update sequence number straight from the on-disk record:

     usn = *(__le16 *)((u8 *)m + le16_to_cpu(m->usa_ofs));

Here m points into the raw $MFT page-cache folio, which still holds
unvalidated, MST-protected bytes: the folio is read by a plain
iomap_read_folio() and neither post_read_mst_fixup() nor
ntfs_mft_record_check() has run on it (both work on private copies).
m->usa_ofs is therefore an untrusted u16, and a corrupted record can put
it past the end of the record so the two-byte read lands outside the
folio.  Reading such a record while creating a file gives, under KASAN:

   BUG: KASAN: use-after-free in ntfs_mft_record_alloc+...
   Read of size 2 at addr ...
    ntfs_mft_record_alloc -> __ntfs_create -> ntfs_create -> path_openat

Only preserve the old update sequence number when usa_ofs is even and in
range, mirroring the check ntfs_mft_record_check() already applies;
otherwise leave usn zero, which the existing restore below skips.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.