---
id: CVE-2025-21648
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: conntrack: clamp maximum hashtable size to INT_MAX

  Use INT_MAX as maximum size for the conntrack hashtable
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: conntrack: clamp maximum hashtable size to INT_MAX

  Use INT_MAX as maximum size for the conntrack hashtable. Otherwise, it
  is possible to hit WARN_ON_ONCE in…
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 >= 4.7.1, < 5.10.234'
  - 'linux_kernel >= 5.11, < 5.15.177'
  - 'linux_kernel >= 5.16, < 6.1.125'
  - 'linux_kernel >= 6.2, < 6.6.72'
  - 'linux_kernel >= 6.7, < 6.12.10'
  - linux_kernel = 4.7
  - linux_kernel = 6.13
patched:
  - linux_kernel 6.12.10
published: '2025-01-19'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21648'
references:
  - url: 'https://git.kernel.org/stable/c/5552b4fd44be3393b930434a7845d8d95a2a3c33'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a965f7f0ea3ae61b9165bed619d5d6da02c75f80'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b1b2353d768f1b80cd7fe045a70adee576b9b338'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b541ba7d1f5a5b7b3e2e22dc9e40e18a7d6dbc13'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d5807dd1328bbc86e059c5de80d1bbee9d58ca3d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f559357d035877b9d0dcd273e0ff83e18e1d46aa'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - 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-265688.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00219
epssPercentile: 0.10986
ingestedAt: '2026-07-14T13:36:54.847Z'
---

## Overview

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

netfilter: conntrack: clamp maximum hashtable size to INT_MAX

Use INT_MAX as maximum size for the conntrack hashtable. Otherwise, it
is possible to hit WARN_ON_ONCE in __kvmalloc_node_noprof() when
resizing hashtable because __GFP_NOWARN is unset. See:

  0708a0afe291 ("mm: Consider __GFP_NOWARN flag for oversized kvmalloc() calls")

Note: hashtable resize is only possible from init_netns.

## Affected

- `linux_kernel >= 4.7.1, < 5.10.234`
- `linux_kernel >= 5.11, < 5.15.177`
- `linux_kernel >= 5.16, < 6.1.125`
- `linux_kernel >= 6.2, < 6.6.72`
- `linux_kernel >= 6.7, < 6.12.10`
- `linux_kernel = 4.7`
- `linux_kernel = 6.13`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.12.10`