---
id: CVE-2026-31438
title: 'netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators

  When a process crashes and the kernel writes a core dump to a 9P
  filesystem, __kernel_write() creat…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 <
    18c2e20b42dd21db599e42d05ddaeeb647b2bb6d
  - >-
    Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 <
    4bc2d72c7695cedf6d4e1a558924903c2b28a78e
  - >-
    Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 <
    00d6df7115f6972370974212de9088087820802e
  - >-
    Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 <
    67e467a11f62ff64ad219dc6aa5459e132c79d14
  - Linux 6.8
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T21:33:22.454848Z'
published: '2026-04-22'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T21:33:51.565Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-31438'
references:
  - url: 'https://git.kernel.org/stable/c/18c2e20b42dd21db599e42d05ddaeeb647b2bb6d'
  - url: 'https://git.kernel.org/stable/c/4bc2d72c7695cedf6d4e1a558924903c2b28a78e'
  - url: 'https://git.kernel.org/stable/c/00d6df7115f6972370974212de9088087820802e'
  - url: 'https://git.kernel.org/stable/c/67e467a11f62ff64ad219dc6aa5459e132c79d14'
tags:
  - cve.org
epss: 0.00122
epssPercentile: 0.01983
ingestedAt: '2026-11-05T22:38:32.138Z'
---

## Overview

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

netfs: Fix kernel BUG in netfs_limit_iter() for ITER_KVEC iterators

When a process crashes and the kernel writes a core dump to a 9P
filesystem, __kernel_write() creates an ITER_KVEC iterator. This
iterator reaches netfs_limit_iter() via netfs_unbuffered_write(), which
only handles ITER_FOLIOQ, ITER_BVEC and ITER_XARRAY iterator types,
hitting the BUG() for any other type.

Fix this by adding netfs_limit_kvec() following the same pattern as
netfs_limit_bvec(), since both kvec and bvec are simple segment arrays
with pointer and length fields. Dispatch it from netfs_limit_iter() when
the iterator type is ITER_KVEC.

## Affected

- `Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 < 18c2e20b42dd21db599e42d05ddaeeb647b2bb6d`
- `Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 < 4bc2d72c7695cedf6d4e1a558924903c2b28a78e`
- `Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 < 00d6df7115f6972370974212de9088087820802e`
- `Linux >= cae932d3aee55035a54415dcea8e7ecf2ec469b5 < 67e467a11f62ff64ad219dc6aa5459e132c79d14`
- `Linux 6.8`

## Remediation

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