---
id: CVE-2026-90203
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Squashfs: check block offset is not negative

  If a negative offset is read off disk (for example the offset into the
  decompressed fragment block), this will cause squas…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  Squashfs: check block offset is not negative

  If a negative offset is read off disk (for example the offset into the
  decompressed fragment block), this will cause squas…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    b169185d5c672b989985c6c2e38cafab2548ba88
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    c2a126fca820ae74872da28de68dc74d4595dc4b
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    95dadf366c117dcdca78a570e6832071deab1ecd
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    3d2f0cb66c909ea2312cdef465165bb9a3ba2d84
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    bbb2218eb072b0a15dc063929200183bd23c2344
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    d0a3729d464fcf516416a41cf304c0c92126ee03
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe
  - >-
    Linux >= f400e12656ab518be107febfe2315fb1eab5a342 <
    e300eb5002925b29be803d2661af07266cfa267e
  - Linux 2.6.29
published: '2026-09-17'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T18:17:46.120'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90203'
references:
  - url: 'https://git.kernel.org/stable/c/3d2f0cb66c909ea2312cdef465165bb9a3ba2d84'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/95dadf366c117dcdca78a570e6832071deab1ecd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b169185d5c672b989985c6c2e38cafab2548ba88'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bbb2218eb072b0a15dc063929200183bd23c2344'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c2a126fca820ae74872da28de68dc74d4595dc4b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d0a3729d464fcf516416a41cf304c0c92126ee03'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e300eb5002925b29be803d2661af07266cfa267e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.00176
epssPercentile: 0.06377
ingestedAt: '2026-09-17T16:21:47.860Z'
---

## Overview

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

Squashfs: check block offset is not negative

If a negative offset is read off disk (for example the offset into the
decompressed fragment block), this will cause squashfs_copy_data() to
perform an out of bounds access.

Fix by checking if offset is negative, and returning 0.  This matches
existing behaviour where an offset beyond the block returns 0 bytes
copied.

To trigger this out of bounds access requires a crafted Squashfs
filesystem and CAP_SYS_ADMIN to mount it.  Unprivileged users will not be
able to mount such a filesystem, but once mounted, an unprivileged user
can trigger the out of bounds access by reading the crafted file with the
negative offset.

## Remediation

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