---
id: CVE-2026-31418
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ipset: drop logically empty buckets in mtype_del

  mtype_del() counts empty slots below n->pos in k, but it only drops the
  bucket when both n->pos and k are z…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ipset: drop logically empty buckets in mtype_del

  mtype_del() counts empty slots below n->pos in k, but it only drops the
  bucket when both n->pos and k are z…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.4.24, < 5.5'
  - 'linux_kernel >= 5.5.8, < 5.6'
  - 'linux_kernel >= 5.6.1, < 5.10.253'
  - 'linux_kernel >= 5.11, < 5.15.203'
  - 'linux_kernel >= 5.16, < 6.1.168'
  - 'linux_kernel >= 6.2, < 6.6.134'
  - 'linux_kernel >= 6.7, < 6.12.81'
  - 'linux_kernel >= 6.13, < 6.18.22'
  - 'linux_kernel >= 6.19, < 6.19.12'
  - linux_kernel = 5.6
  - linux_kernel = 7.0
patched:
  - linux_kernel 6.19.12
published: '2026-04-13'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:19:03.653'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-31418'
references:
  - url: 'https://git.kernel.org/stable/c/58f3a14826d4e6b0d5421f1a64be280b48601ea2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/68ca0eea0af02bed36c5e2c13e9fa1647c31a7d4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6cea34d7ec6829b62f521a37a287f670144a2233'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9862ef9ab0a116c6dca98842aab7de13a252ae02'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ad92ee87462f9a3061361d392e9dbfe2e5c1c9fb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b7eef00f08b92b0b9efe8ae0df6d0005e6199323'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c098ff857e7ca923539164af5b3c2fe3e8f8afaf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ceacaa76f221a6577aba945bb8873c2e640aeba4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.0012
epssPercentile: 0.01835
ingestedAt: '2026-09-08T15:33:26.991Z'
---

## Overview

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

netfilter: ipset: drop logically empty buckets in mtype_del

mtype_del() counts empty slots below n->pos in k, but it only drops the
bucket when both n->pos and k are zero. This misses buckets whose live
entries have all been removed while n->pos still points past deleted slots.

Treat a bucket as empty when all positions below n->pos are unused and
release it directly instead of shrinking it further.

## Affected

- `linux_kernel >= 5.4.24, < 5.5`
- `linux_kernel >= 5.5.8, < 5.6`
- `linux_kernel >= 5.6.1, < 5.10.253`
- `linux_kernel >= 5.11, < 5.15.203`
- `linux_kernel >= 5.16, < 6.1.168`
- `linux_kernel >= 6.2, < 6.6.134`
- `linux_kernel >= 6.7, < 6.12.81`
- `linux_kernel >= 6.13, < 6.18.22`
- `linux_kernel >= 6.19, < 6.19.12`
- `linux_kernel = 5.6`
- `linux_kernel = 7.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.12`