---
id: CVE-2026-74492
title: 'netfilter: ipset: do not update comments from kernel-side hash adds'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ipset: do not update comments from kernel-side hash adds

  mtype_resize() copies comment pointers with memcpy(), not the comment
  objects themselves. During th…
severity: high
cvss: 8.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    6f13f4d52d06986c18f12e8bffaab944dd27ceab
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    f9d6cabff1fca010562dcdb0d22b296bdca3ba5a
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    16bfa7be2d76ca1e0aacfa363482e1bf8ab5042a
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    661ff9c0cfbe07f8eed920dde9f7781491738207
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    c710e9bf38e4e71a8db85d26a0f70c0674664207
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    4ae701848e4ba9e9713375fb7d82218cbd309da2
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    77dbb248a5cc7a5270cd37bbb0b635bf059a872a
  - >-
    Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 <
    f30415929be8aeb002d557c8d3f7ab2d2188003a
  - Linux 5dd9488ae41070b69d2f4acb580f77db5705f9ca
  - Linux a469bab3386aebff33c59506f3a95e35b91118fd
  - Linux >= 5.4.24 < 5.5
  - Linux >= 5.5.8 < 5.6
  - Linux 5.6
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:58:08.112220Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:05:49.918Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74492'
references:
  - url: 'https://git.kernel.org/stable/c/6f13f4d52d06986c18f12e8bffaab944dd27ceab'
  - url: 'https://git.kernel.org/stable/c/f9d6cabff1fca010562dcdb0d22b296bdca3ba5a'
  - url: 'https://git.kernel.org/stable/c/16bfa7be2d76ca1e0aacfa363482e1bf8ab5042a'
  - url: 'https://git.kernel.org/stable/c/661ff9c0cfbe07f8eed920dde9f7781491738207'
  - url: 'https://git.kernel.org/stable/c/c710e9bf38e4e71a8db85d26a0f70c0674664207'
  - url: 'https://git.kernel.org/stable/c/4ae701848e4ba9e9713375fb7d82218cbd309da2'
  - url: 'https://git.kernel.org/stable/c/77dbb248a5cc7a5270cd37bbb0b635bf059a872a'
  - url: 'https://git.kernel.org/stable/c/f30415929be8aeb002d557c8d3f7ab2d2188003a'
tags:
  - cve.org
epss: 0.00142
epssPercentile: 0.03119
ingestedAt: '2026-10-16T19:46:24.357Z'
---

## Overview

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

netfilter: ipset: do not update comments from kernel-side hash adds

mtype_resize() copies comment pointers with memcpy(), not the comment
objects themselves. During the window after an entry has been copied but
before the table swap and backlog replay, the old table is still
published for packet-side updates while the replacement-table entry
already holds the same ip_set_comment_rcu pointer.

If xt_SET --add-set ... --exist hits that old entry in this window,
mtype_add() calls ip_set_init_comment() even though packet-side adds
carry no comment payload. That call frees the shared comment through the
old entry, so the replacement-table entry now holds a stale pointer.
When the queued add is replayed on the new table, mtype_add() calls
ip_set_init_comment() again and strlen() dereferences the stale pointer.

Fix this in mtype_add() by skipping ip_set_init_comment() when
ext->target marks a packet-side add. Userspace adds still update
comments, while packet-side adds can no longer free comment storage
shared with a resize copy.

## Affected

- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < 6f13f4d52d06986c18f12e8bffaab944dd27ceab`
- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < f9d6cabff1fca010562dcdb0d22b296bdca3ba5a`
- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < 16bfa7be2d76ca1e0aacfa363482e1bf8ab5042a`
- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < 661ff9c0cfbe07f8eed920dde9f7781491738207`
- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < c710e9bf38e4e71a8db85d26a0f70c0674664207`
- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < 4ae701848e4ba9e9713375fb7d82218cbd309da2`
- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < 77dbb248a5cc7a5270cd37bbb0b635bf059a872a`
- `Linux >= f66ee0410b1c3481ee75e5db9b34547b4d582465 < f30415929be8aeb002d557c8d3f7ab2d2188003a`
- `Linux 5dd9488ae41070b69d2f4acb580f77db5705f9ca`
- `Linux a469bab3386aebff33c59506f3a95e35b91118fd`
- `Linux >= 5.4.24 < 5.5`
- `Linux >= 5.5.8 < 5.6`
- `Linux 5.6`

## Remediation

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