---
id: CVE-2025-21766
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv4: use RCU protection in __ip_rt_update_pmtu()

  __ip_rt_update_pmtu() must use RCU protection to make
  sure the net structure it reads does not disappear.
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv4: use RCU protection in __ip_rt_update_pmtu()

  __ip_rt_update_pmtu() must use RCU protection to make
  sure the net structure it reads does not disappear.
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 4.14.200, < 4.15'
  - 'linux_kernel >= 4.19.148, < 4.20'
  - 'linux_kernel >= 5.4.68, < 5.5'
  - 'linux_kernel >= 5.8.12, < 5.9'
  - 'linux_kernel >= 5.9.1, < 5.15.179'
  - 'linux_kernel >= 5.16, < 6.1.129'
  - 'linux_kernel >= 6.2, < 6.6.79'
  - 'linux_kernel >= 6.7, < 6.12.16'
  - 'linux_kernel >= 6.13, < 6.13.4'
  - linux_kernel = 5.9
  - linux_kernel = 6.14
patched:
  - linux_kernel 6.13.4
published: '2025-02-27'
updated: '2026-07-30'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21766'
references:
  - url: 'https://git.kernel.org/stable/c/139512191bd06f1b496117c76372b2ce372c9a41'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4583748b65dee4d61bd50a2214715b4237bc152a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9b1766d1ff5fe496aabe9fc5f4e34e53f35c11c4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a39f61d212d822b3062d7f70fa0588e50e55664e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ce3c6165fce0f06305c806696882a3ad4b90e33f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ea07480b23225942208f1b754fea1e7ec486d37e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.00541
epssPercentile: 0.42996
ingestedAt: '2026-07-30T06:53:09.843Z'
---

## Overview

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

ipv4: use RCU protection in __ip_rt_update_pmtu()

__ip_rt_update_pmtu() must use RCU protection to make
sure the net structure it reads does not disappear.

## Affected

- `linux_kernel >= 4.14.200, < 4.15`
- `linux_kernel >= 4.19.148, < 4.20`
- `linux_kernel >= 5.4.68, < 5.5`
- `linux_kernel >= 5.8.12, < 5.9`
- `linux_kernel >= 5.9.1, < 5.15.179`
- `linux_kernel >= 5.16, < 6.1.129`
- `linux_kernel >= 6.2, < 6.6.79`
- `linux_kernel >= 6.7, < 6.12.16`
- `linux_kernel >= 6.13, < 6.13.4`
- `linux_kernel = 5.9`
- `linux_kernel = 6.14`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.13.4`