---
id: CVE-2026-31418
title: 'netfilter: ipset: drop logically empty buckets in mtype_del'
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: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    c098ff857e7ca923539164af5b3c2fe3e8f8afaf
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    58f3a14826d4e6b0d5421f1a64be280b48601ea2
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    ad92ee87462f9a3061361d392e9dbfe2e5c1c9fb
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    6cea34d7ec6829b62f521a37a287f670144a2233
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    b7eef00f08b92b0b9efe8ae0df6d0005e6199323
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    68ca0eea0af02bed36c5e2c13e9fa1647c31a7d4
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    ceacaa76f221a6577aba945bb8873c2e640aeba4
  - >-
    Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 <
    9862ef9ab0a116c6dca98842aab7de13a252ae02
  - Linux 6c717726f341fd8f39a3ec2dcf5d98d9d28a2769
  - Linux d2997d64dfa65082236bca1efd596b6c935daf5e
  - Linux >= 5.4.24 < 5.5
  - Linux >= 5.5.8 < 5.6
  - Linux 5.6
published: '2026-04-13'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:46:55.323Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-31418'
references:
  - url: 'https://git.kernel.org/stable/c/c098ff857e7ca923539164af5b3c2fe3e8f8afaf'
  - url: 'https://git.kernel.org/stable/c/58f3a14826d4e6b0d5421f1a64be280b48601ea2'
  - url: 'https://git.kernel.org/stable/c/ad92ee87462f9a3061361d392e9dbfe2e5c1c9fb'
  - url: 'https://git.kernel.org/stable/c/6cea34d7ec6829b62f521a37a287f670144a2233'
  - url: 'https://git.kernel.org/stable/c/b7eef00f08b92b0b9efe8ae0df6d0005e6199323'
  - url: 'https://git.kernel.org/stable/c/68ca0eea0af02bed36c5e2c13e9fa1647c31a7d4'
  - url: 'https://git.kernel.org/stable/c/ceacaa76f221a6577aba945bb8873c2e640aeba4'
  - url: 'https://git.kernel.org/stable/c/9862ef9ab0a116c6dca98842aab7de13a252ae02'
tags:
  - cve.org
epss: 0.00171
epssPercentile: 0.05625
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 >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < c098ff857e7ca923539164af5b3c2fe3e8f8afaf`
- `Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < 58f3a14826d4e6b0d5421f1a64be280b48601ea2`
- `Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < ad92ee87462f9a3061361d392e9dbfe2e5c1c9fb`
- `Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < 6cea34d7ec6829b62f521a37a287f670144a2233`
- `Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < b7eef00f08b92b0b9efe8ae0df6d0005e6199323`
- `Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < 68ca0eea0af02bed36c5e2c13e9fa1647c31a7d4`
- `Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < ceacaa76f221a6577aba945bb8873c2e640aeba4`
- `Linux >= 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 < 9862ef9ab0a116c6dca98842aab7de13a252ae02`
- `Linux 6c717726f341fd8f39a3ec2dcf5d98d9d28a2769`
- `Linux d2997d64dfa65082236bca1efd596b6c935daf5e`
- `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.