---
id: CVE-2026-23381
title: 'net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled

  When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never
  initialized because inet6_init() e…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    a9d712ccfeef737c0e700a4b5b98f310e07b6b60
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    a5c56e65b685360dd3f2278aeff8c21061feb665
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    7a894eb5de246d79f13105c55a67381039a24d44
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    a12cdaa3375f0bd3c8f4e564be7c143529abfe5b
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    aa73deb3b6b730ec280d45b3f423bfa9e17bc122
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    33dec6f10777d5a8f71c0a200f690da5ae3c2e55
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    20ef5c25422f97dd09d751e5ae6c18406cdc78e6
  - >-
    Linux >= ed842faeb2bd49256f00485402f3113205f91d30 <
    e5e890630533bdc15b26a34bb8e7ef539bdf1322
  - Linux 4.15
published: '2026-03-25'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:45:53.238Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-23381'
references:
  - url: 'https://git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60'
  - url: 'https://git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665'
  - url: 'https://git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44'
  - url: 'https://git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b'
  - url: 'https://git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122'
  - url: 'https://git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55'
  - url: 'https://git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6'
  - url: 'https://git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322'
tags:
  - cve.org
epss: 0.0012
epssPercentile: 0.0161
ingestedAt: '2026-09-08T15:33:26.992Z'
---

## Overview

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

net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled

When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never
initialized because inet6_init() exits before ndisc_init() is called
which initializes it. Then, if neigh_suppress is enabled and an ICMPv6
Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will
dereference ipv6_stub->nd_tbl which is NULL, passing it to
neigh_lookup(). This causes a kernel NULL pointer dereference.

 BUG: kernel NULL pointer dereference, address: 0000000000000268
 Oops: 0000 [#1] PREEMPT SMP NOPTI
 [...]
 RIP: 0010:neigh_lookup+0x16/0xe0
 [...]
 Call Trace:
  <IRQ>
  ? neigh_lookup+0x16/0xe0
  br_do_suppress_nd+0x160/0x290 [bridge]
  br_handle_frame_finish+0x500/0x620 [bridge]
  br_handle_frame+0x353/0x440 [bridge]
  __netif_receive_skb_core.constprop.0+0x298/0x1110
  __netif_receive_skb_one_core+0x3d/0xa0
  process_backlog+0xa0/0x140
  __napi_poll+0x2c/0x170
  net_rx_action+0x2c4/0x3a0
  handle_softirqs+0xd0/0x270
  do_softirq+0x3f/0x60

Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in
the callers. This is in essence disabling NS/NA suppression when IPv6 is
disabled.

## Affected

- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < a9d712ccfeef737c0e700a4b5b98f310e07b6b60`
- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < a5c56e65b685360dd3f2278aeff8c21061feb665`
- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < 7a894eb5de246d79f13105c55a67381039a24d44`
- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < a12cdaa3375f0bd3c8f4e564be7c143529abfe5b`
- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < aa73deb3b6b730ec280d45b3f423bfa9e17bc122`
- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < 33dec6f10777d5a8f71c0a200f690da5ae3c2e55`
- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < 20ef5c25422f97dd09d751e5ae6c18406cdc78e6`
- `Linux >= ed842faeb2bd49256f00485402f3113205f91d30 < e5e890630533bdc15b26a34bb8e7ef539bdf1322`
- `Linux 4.15`

## Remediation

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