---
id: CVE-2026-72436
title: 'netfilter: ipset: Don''t use test_bit() in lockless RCU readers in hash types'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types

  Sashiko pointed out that there are a few lockless RCU readers
  using test_bit() which is a …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 <
    c107233d2ff4fd7cef5d02f9124b99194957a710
  - >-
    Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 <
    6329d3a9afe715fddda0460cfa46b496d61c2fe0
  - >-
    Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 <
    7445fe965b7d8756070a40e80f8b73348ccda1d7
  - >-
    Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 <
    c4d257734e91bfcdc71d41843392dd6400b5bb1b
  - >-
    Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 <
    3219d74e4536658c937fd878a327257b86ce80dd
  - >-
    Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 <
    e4b4984e28c16406ecb318444dea4a8bf47def3e
  - Linux 4.2
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T18:49:57.755944Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:55:24.058Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72436'
references:
  - url: 'https://git.kernel.org/stable/c/c107233d2ff4fd7cef5d02f9124b99194957a710'
  - url: 'https://git.kernel.org/stable/c/6329d3a9afe715fddda0460cfa46b496d61c2fe0'
  - url: 'https://git.kernel.org/stable/c/7445fe965b7d8756070a40e80f8b73348ccda1d7'
  - url: 'https://git.kernel.org/stable/c/c4d257734e91bfcdc71d41843392dd6400b5bb1b'
  - url: 'https://git.kernel.org/stable/c/3219d74e4536658c937fd878a327257b86ce80dd'
  - url: 'https://git.kernel.org/stable/c/e4b4984e28c16406ecb318444dea4a8bf47def3e'
tags:
  - cve.org
epss: 0.00721
epssPercentile: 0.5301
ingestedAt: '2026-10-16T19:46:24.395Z'
---

## Overview

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

netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types

Sashiko pointed out that there are a few lockless RCU readers
using test_bit() which is a relaxed atomic operation and
provides no memory barrier guarantees. Use test_bit_acquire()
instead where the operation may run parallel with add/del/gc,
i.e. is not one from the next cases

- protected by region lock
- in a set destroy phase
- in a new/temporary set creation phase

## Affected

- `Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 < c107233d2ff4fd7cef5d02f9124b99194957a710`
- `Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 < 6329d3a9afe715fddda0460cfa46b496d61c2fe0`
- `Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 < 7445fe965b7d8756070a40e80f8b73348ccda1d7`
- `Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 < c4d257734e91bfcdc71d41843392dd6400b5bb1b`
- `Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 < 3219d74e4536658c937fd878a327257b86ce80dd`
- `Linux >= 18f84d41d34fa35d0d64bbaea01fe664553ecc06 < e4b4984e28c16406ecb318444dea4a8bf47def3e`
- `Linux 4.2`

## Remediation

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