---
id: CVE-2026-43040
title: >-
  net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to
  zero to prevent an info-leak
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: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    11d7fe97421cfc81549940c20ed5ac9472d6db05
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    7f56d87e527bb5a13c3e8b0d5840cb6332822f6d
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    4f810c686fde509d1cdaa706322d9d2531f8f1a4
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    b485eef3d97b7aae55ce669b6de555ec81f3d21c
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    ef3645606e4a635d5062a492f22b7f490852ee67
  - >-
    Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf <
    ae05340ccaa9d347fe85415609e075545bec589f
  - Linux 2.6.24
published: '2026-05-01'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:48:41.660Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43040'
references:
  - url: 'https://git.kernel.org/stable/c/1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c'
  - url: 'https://git.kernel.org/stable/c/2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648'
  - url: 'https://git.kernel.org/stable/c/11d7fe97421cfc81549940c20ed5ac9472d6db05'
  - url: 'https://git.kernel.org/stable/c/7f56d87e527bb5a13c3e8b0d5840cb6332822f6d'
  - url: 'https://git.kernel.org/stable/c/4f810c686fde509d1cdaa706322d9d2531f8f1a4'
  - url: 'https://git.kernel.org/stable/c/b485eef3d97b7aae55ce669b6de555ec81f3d21c'
  - url: 'https://git.kernel.org/stable/c/ef3645606e4a635d5062a492f22b7f490852ee67'
  - url: 'https://git.kernel.org/stable/c/ae05340ccaa9d347fe85415609e075545bec589f'
tags:
  - cve.org
epss: 0.00174
epssPercentile: 0.06033
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 >= 31910575a9de61e78065e93846e8e7a4894a18bf < 1da9023f6b071a38e5430ffbce4b70b2b1ac4f9c`
- `Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf < 2fe4d0ba690a69ad6ae9f7ab9bdc96e02610b648`
- `Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf < 11d7fe97421cfc81549940c20ed5ac9472d6db05`
- `Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf < 7f56d87e527bb5a13c3e8b0d5840cb6332822f6d`
- `Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf < 4f810c686fde509d1cdaa706322d9d2531f8f1a4`
- `Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf < b485eef3d97b7aae55ce669b6de555ec81f3d21c`
- `Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf < ef3645606e4a635d5062a492f22b7f490852ee67`
- `Linux >= 31910575a9de61e78065e93846e8e7a4894a18bf < ae05340ccaa9d347fe85415609e075545bec589f`
- `Linux 2.6.24`

## Remediation

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