---
id: CVE-2026-46124
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  isofs: validate block number from NFS file handle in isofs_export_iget

  isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker-
  controlled block number (ifid->b…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  isofs: validate block number from NFS file handle in isofs_export_iget

  isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker-
  controlled block number (ifid->b…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.4.293, < 5.5'
  - 'linux_kernel >= 5.10.237, < 5.10.258'
  - 'linux_kernel >= 5.15.181, < 5.15.209'
  - 'linux_kernel >= 6.1.135, < 6.1.175'
  - 'linux_kernel >= 6.6.88, < 6.6.140'
  - 'linux_kernel >= 6.12.25, < 6.12.88'
  - 'linux_kernel >= 6.14.4, < 6.15'
  - 'linux_kernel >= 6.15.1, < 6.18.30'
  - 'linux_kernel >= 6.19, < 7.0.7'
  - linux_kernel = 6.15
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.7
published: '2026-05-28'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:19:44.953'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-46124'
references:
  - url: 'https://git.kernel.org/stable/c/0a1af74ae2177bda3aee0837a0546309aa539d0d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/24376458138387fb251e782e624c7776e9826796'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/31dbb4ba0f719ae7774e4c0c95172c9bf81692f5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/908a76f0b1038035e6ebb4f2293ce079f92e0a02'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bb0988ed4f2e26d59bbb58f644cb3a55b7521e21'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ee0024f5a7e3c73aa253869fae9650ae054093ca'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-784472.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00579
epssPercentile: 0.46362
ingestedAt: '2026-10-15T03:30:12.889Z'
---

## Overview

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

isofs: validate block number from NFS file handle in isofs_export_iget

isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker-
controlled block number (ifid->block or ifid->parent_block) from
the NFS file handle to isofs_export_iget(), which only rejects
block == 0 before calling isofs_iget() and ultimately sb_bread().
A crafted file handle with fh_len sufficient to pass the check
added by commit 0405d4b63d08 ("isofs: Prevent the use of too small
fid") can still drive the server to read any in-range block on the
backing device as if it were an iso_directory_record.  That earlier
fix was assigned CVE-2025-37780.

sb_bread() on an out-of-range block returns NULL cleanly via the
EIO path, so there is no memory-safety violation.  For in-range
reads of adjacent-partition data on the same block device, the
unrelated bytes end up in iso_inode_info fields that reach the NFS
client as dentry metadata.  The deployment surface (isofs exported
over NFS from loop-mounted images) is narrow and requires an
authenticated NFS peer, but the malformed-file-handle class is
reportable as hardening next to the existing CVE-2025-37780 fix.

Reject block >= ISOFS_SB(sb)->s_nzones in isofs_export_iget() so
the check covers both isofs_fh_to_dentry() and isofs_fh_to_parent()
call sites with a single line.

## Affected

- `linux_kernel >= 5.4.293, < 5.5`
- `linux_kernel >= 5.10.237, < 5.10.258`
- `linux_kernel >= 5.15.181, < 5.15.209`
- `linux_kernel >= 6.1.135, < 6.1.175`
- `linux_kernel >= 6.6.88, < 6.6.140`
- `linux_kernel >= 6.12.25, < 6.12.88`
- `linux_kernel >= 6.14.4, < 6.15`
- `linux_kernel >= 6.15.1, < 6.18.30`
- `linux_kernel >= 6.19, < 7.0.7`
- `linux_kernel = 6.15`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.7`