---
id: CVE-2026-43040
title: >-
  In the Linux kernel, the following vulnerability has been resolved:


  net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to
  zero to prevent an info-leak


  When processing Router Advertisements with user options the …
summary: >-
  In the Linux kernel, the following vulnerability has been resolved:


  net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to
  zero to prevent an info-leak


  When processing Router Advertisements with user options the …
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-909
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.24, < 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 = 7.0
patched:
  - linux_kernel 6.19.12
published: '2026-05-01'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:19:29.050'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-43040'
references:
  - url: 'https://git.kernel.org/stable/c/11d7fe97421cfc81549940c20ed5ac9472d6db05'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4f810c686fde509d1cdaa706322d9d2531f8f1a4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7f56d87e527bb5a13c3e8b0d5840cb6332822f6d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ae05340ccaa9d347fe85415609e075545bec589f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b485eef3d97b7aae55ce669b6de555ec81f3d21c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ef3645606e4a635d5062a492f22b7f490852ee67'
    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: 0.00129
epssPercentile: 0.02508
ingestedAt: '2026-09-08T15:33:26.989Z'
---

## Overview

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

net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak

When processing Router Advertisements with user options the kernel
builds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct
has three padding fields that are never zeroed and can leak kernel data

The fix is simple, just zeroes the padding fields.

## Affected

- `linux_kernel >= 2.6.24, < 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 = 7.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.12`