---
id: CVE-2025-40198
title: 'ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()

  Unlike other strings in the ext4 superblock, we rely on tune2fs to
  make sure s_mount_opts is N…
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 >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 <
    7bf46ff83a0ef11836e38ebd72cdc5107209342d
  - >-
    Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 <
    b2bac84fde28fb6a88817b8b761abda17a1d300b
  - >-
    Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 <
    e651294218d2684302ee5ed95ccf381646f3e5b4
  - >-
    Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 <
    01829af7656b56d83682b3491265d583d502e502
  - >-
    Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 <
    2a0cf438320cdb783e0378570744c0ef0d83e934
  - >-
    Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 <
    a6e94557cd05adc82fae0400f6e17745563e5412
  - >-
    Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 <
    8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8
  - Linux 2.6.36
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:57:54.146489Z'
published: '2025-11-12'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:02:40.274Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-40198'
references:
  - url: 'https://git.kernel.org/stable/c/7bf46ff83a0ef11836e38ebd72cdc5107209342d'
  - url: 'https://git.kernel.org/stable/c/b2bac84fde28fb6a88817b8b761abda17a1d300b'
  - url: 'https://git.kernel.org/stable/c/e651294218d2684302ee5ed95ccf381646f3e5b4'
  - url: 'https://git.kernel.org/stable/c/01829af7656b56d83682b3491265d583d502e502'
  - url: 'https://git.kernel.org/stable/c/2a0cf438320cdb783e0378570744c0ef0d83e934'
  - url: 'https://git.kernel.org/stable/c/a6e94557cd05adc82fae0400f6e17745563e5412'
  - url: 'https://git.kernel.org/stable/c/8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8'
tags:
  - cve.org
epss: 0.00164
epssPercentile: 0.05247
ingestedAt: '2026-10-15T22:48:25.550Z'
---

## Overview

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

ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()

Unlike other strings in the ext4 superblock, we rely on tune2fs to
make sure s_mount_opts is NUL terminated.  Harden
parse_apply_sb_mount_options() by treating s_mount_opts as a potential
__nonstring.

## Affected

- `Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 < 7bf46ff83a0ef11836e38ebd72cdc5107209342d`
- `Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 < b2bac84fde28fb6a88817b8b761abda17a1d300b`
- `Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 < e651294218d2684302ee5ed95ccf381646f3e5b4`
- `Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 < 01829af7656b56d83682b3491265d583d502e502`
- `Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 < 2a0cf438320cdb783e0378570744c0ef0d83e934`
- `Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 < a6e94557cd05adc82fae0400f6e17745563e5412`
- `Linux >= 8b67f04ab9de5d8f3a71aef72bf02c995a506db5 < 8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8`
- `Linux 2.6.36`

## Remediation

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