---
id: CVE-2026-31447
title: 'ext4: reject mount if bigalloc with s_first_data_block != 0'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ext4: reject mount if bigalloc with s_first_data_block != 0

  bigalloc with s_first_data_block != 0 is not supported, reject mounting
  it.
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    5ad6d994255e27a3254079dfb50ca861fc31f2d0
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    3a926957cc95899ef88529710836edadc03c71a1
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    7b58c110b4e1f028eb38eec9ed3555e9be81c8b0
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    b77de3fceafbb39f30e4ff5dc986f863d5456417
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    d787d3ae96648dc14a3b7ca8fde817177e82c1c7
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    ad1f6d608f33f59d21a3d025615d6786a6443998
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    7d5b04290156c3fc316eecc86a4f9d201ab7d44a
  - >-
    Linux >= 281b59959707dfae03ce038cdf231bf4904e170c <
    3822743dc20386d9897e999dbb990befa3a5b3f8
  - Linux 3.2
published: '2026-04-22'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:47:11.487Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-31447'
references:
  - url: 'https://git.kernel.org/stable/c/5ad6d994255e27a3254079dfb50ca861fc31f2d0'
  - url: 'https://git.kernel.org/stable/c/3a926957cc95899ef88529710836edadc03c71a1'
  - url: 'https://git.kernel.org/stable/c/7b58c110b4e1f028eb38eec9ed3555e9be81c8b0'
  - url: 'https://git.kernel.org/stable/c/b77de3fceafbb39f30e4ff5dc986f863d5456417'
  - url: 'https://git.kernel.org/stable/c/d787d3ae96648dc14a3b7ca8fde817177e82c1c7'
  - url: 'https://git.kernel.org/stable/c/ad1f6d608f33f59d21a3d025615d6786a6443998'
  - url: 'https://git.kernel.org/stable/c/7d5b04290156c3fc316eecc86a4f9d201ab7d44a'
  - url: 'https://git.kernel.org/stable/c/3822743dc20386d9897e999dbb990befa3a5b3f8'
tags:
  - cve.org
epss: 0.00197
epssPercentile: 0.08341
ingestedAt: '2026-09-08T15:33:26.990Z'
---

## Overview

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

ext4: reject mount if bigalloc with s_first_data_block != 0

bigalloc with s_first_data_block != 0 is not supported, reject mounting
it.

## Affected

- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < 5ad6d994255e27a3254079dfb50ca861fc31f2d0`
- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < 3a926957cc95899ef88529710836edadc03c71a1`
- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < 7b58c110b4e1f028eb38eec9ed3555e9be81c8b0`
- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < b77de3fceafbb39f30e4ff5dc986f863d5456417`
- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < d787d3ae96648dc14a3b7ca8fde817177e82c1c7`
- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < ad1f6d608f33f59d21a3d025615d6786a6443998`
- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < 7d5b04290156c3fc316eecc86a4f9d201ab7d44a`
- `Linux >= 281b59959707dfae03ce038cdf231bf4904e170c < 3822743dc20386d9897e999dbb990befa3a5b3f8`
- `Linux 3.2`

## Remediation

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