---
id: CVE-2026-72191
title: 'ntfs3: validate split-point offset in indx_insert_into_buffer'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ntfs3: validate split-point offset in indx_insert_into_buffer

  indx_insert_into_buffer() computes

      used = used1 - to_copy - sp_size;
      memmove(de_t, Add2Ptr(sp, s…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 <
    8e4ba5a38c155bb3c1c11e63cd285b178cdb099e
  - >-
    Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 <
    4c2f648139a0a86f4486170f72e24fedd4fae74e
  - >-
    Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 <
    b232eb5c9fe11ec2368e9b565db69c724c35fbd2
  - >-
    Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 <
    7bf74e6baf810fe325f111996496c678fc6e244f
  - >-
    Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 <
    f3624cc069195001c88df7a291af215f2133ff2c
  - >-
    Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 <
    1758a564b6ebe7f4a82f23c9851d1cae15549457
  - >-
    Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 <
    f1df9d771df47aa40de6d70949c28720ae1e430d
  - Linux 5.15
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T18:43:30.355468Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:45:00.783Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72191'
references:
  - url: 'https://git.kernel.org/stable/c/8e4ba5a38c155bb3c1c11e63cd285b178cdb099e'
  - url: 'https://git.kernel.org/stable/c/4c2f648139a0a86f4486170f72e24fedd4fae74e'
  - url: 'https://git.kernel.org/stable/c/b232eb5c9fe11ec2368e9b565db69c724c35fbd2'
  - url: 'https://git.kernel.org/stable/c/7bf74e6baf810fe325f111996496c678fc6e244f'
  - url: 'https://git.kernel.org/stable/c/f3624cc069195001c88df7a291af215f2133ff2c'
  - url: 'https://git.kernel.org/stable/c/1758a564b6ebe7f4a82f23c9851d1cae15549457'
  - url: 'https://git.kernel.org/stable/c/f1df9d771df47aa40de6d70949c28720ae1e430d'
tags:
  - cve.org
epss: 0.00697
epssPercentile: 0.52104
ingestedAt: '2026-10-16T19:46:24.423Z'
---

## Overview

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

ntfs3: validate split-point offset in indx_insert_into_buffer

indx_insert_into_buffer() computes

    used = used1 - to_copy - sp_size;
    memmove(de_t, Add2Ptr(sp, sp_size), used - le32_to_cpu(hdr1->de_off));

where sp and sp_size come from hdr_find_split().  hdr_find_split()
walks entries by le16_to_cpu(e->size) without validating that each
step stays within hdr->used or that the size field is at least
sizeof(struct NTFS_DE).  index_hdr_check(), the on-load gatekeeper,
only validates header-level fields (used, total, de_off) and does
not walk per-entry sizes.

A crafted NTFS image whose leaf INDEX_HDR reports used == total but
contains one interior NTFS_DE with size = 0xFFF0 therefore passes
validation, descends to indx_insert_into_buffer() through the
ntfs_create() -> indx_insert_entry() path, and makes hdr_find_split()
return an sp whose sp_size (0xFFF0) greatly exceeds the remaining
bytes in the buffer.  The u32 subtraction underflows and the memmove
count becomes a near-4-GiB value, producing an out-of-bounds kernel
write that corrupts adjacent allocations and panics the kernel.

Reproduced on 7.0.0-rc7 with UML + KASAN via a crafted image and a
single 'touch' inside the mounted directory; crash site resolves to
fs/ntfs3/index.c at the memmove.  Trigger requires only local mount
of an attacker-supplied filesystem image (USB, loopback, or removable
media auto-mount).

Reject the split whenever the chosen sp plus its declared size
already extends past hdr1->used.  This is the minimal fix; it
preserves the existing hdr_find_split() contract and relies on the
same out: cleanup path as the pre-existing error returns.

A prior OOB read in the very same indx_insert_into_buffer() memmove
was fixed in commit b8c44949044e ("fs/ntfs3: Fix OOB read in
indx_insert_into_buffer") by tightening hdr_find_e(), but that fix
does not cover the split-point size field path addressed here: sp is
returned by hdr_find_split(), not hdr_find_e(), and the underflow is
driven by sp->size rather than hdr->used exceeding hdr->total.

## Affected

- `Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 < 8e4ba5a38c155bb3c1c11e63cd285b178cdb099e`
- `Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 < 4c2f648139a0a86f4486170f72e24fedd4fae74e`
- `Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 < b232eb5c9fe11ec2368e9b565db69c724c35fbd2`
- `Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 < 7bf74e6baf810fe325f111996496c678fc6e244f`
- `Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 < f3624cc069195001c88df7a291af215f2133ff2c`
- `Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 < 1758a564b6ebe7f4a82f23c9851d1cae15549457`
- `Linux >= 82cae269cfa953032fbb8980a7d554d60fb00b17 < f1df9d771df47aa40de6d70949c28720ae1e430d`
- `Linux 5.15`

## Remediation

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