---
id: CVE-2026-23304
title: 'ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()

  l3mdev_master_dev_rcu() can return NULL when the slave device is being
  un-slaved from a VRF. All other callers dea…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    d542e2ac7f9e288d49735be0775611547ca4e0ee
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    a73fe9f4ae84a239d5b2686f47a58c158aee2eb4
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    4a48fe59f29f673a3d042d679f26629a9c3e29d4
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    581800298313c9fd75e94985e6d37d21b7e35d34
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    3310fc11fc47387d1dd4759b0bc961643ea11c7f
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    0b5a7826020706057cc5a9d9009e667027f221ee
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    ae88c8256547b63980770a9ea7be73a15900d27e
  - >-
    Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d <
    2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a
  - Linux 4.14
published: '2026-03-25'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:45:32.838Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-23304'
references:
  - url: 'https://git.kernel.org/stable/c/d542e2ac7f9e288d49735be0775611547ca4e0ee'
  - url: 'https://git.kernel.org/stable/c/a73fe9f4ae84a239d5b2686f47a58c158aee2eb4'
  - url: 'https://git.kernel.org/stable/c/4a48fe59f29f673a3d042d679f26629a9c3e29d4'
  - url: 'https://git.kernel.org/stable/c/581800298313c9fd75e94985e6d37d21b7e35d34'
  - url: 'https://git.kernel.org/stable/c/3310fc11fc47387d1dd4759b0bc961643ea11c7f'
  - url: 'https://git.kernel.org/stable/c/0b5a7826020706057cc5a9d9009e667027f221ee'
  - url: 'https://git.kernel.org/stable/c/ae88c8256547b63980770a9ea7be73a15900d27e'
  - url: 'https://git.kernel.org/stable/c/2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a'
tags:
  - cve.org
epss: 0.00129
epssPercentile: 0.02071
ingestedAt: '2026-09-08T15:33:26.993Z'
---

## Overview

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

ipv6: fix NULL pointer deref in ip6_rt_get_dev_rcu()

l3mdev_master_dev_rcu() can return NULL when the slave device is being
un-slaved from a VRF. All other callers deal with this, but we lost
the fallback to loopback in ip6_rt_pcpu_alloc() -> ip6_rt_get_dev_rcu()
with commit 4832c30d5458 ("net: ipv6: put host and anycast routes on
device with address").

  KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f]
  RIP: 0010:ip6_rt_pcpu_alloc (net/ipv6/route.c:1418)
  Call Trace:
   ip6_pol_route (net/ipv6/route.c:2318)
   fib6_rule_lookup (net/ipv6/fib6_rules.c:115)
   ip6_route_output_flags (net/ipv6/route.c:2607)
   vrf_process_v6_outbound (drivers/net/vrf.c:437)

I was tempted to rework the un-slaving code to clear the flag first
and insert synchronize_rcu() before we remove the upper. But looks like
the explicit fallback to loopback_dev is an established pattern.
And I guess avoiding the synchronize_rcu() is nice, too.

## Affected

- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < d542e2ac7f9e288d49735be0775611547ca4e0ee`
- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < a73fe9f4ae84a239d5b2686f47a58c158aee2eb4`
- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < 4a48fe59f29f673a3d042d679f26629a9c3e29d4`
- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < 581800298313c9fd75e94985e6d37d21b7e35d34`
- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < 3310fc11fc47387d1dd4759b0bc961643ea11c7f`
- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < 0b5a7826020706057cc5a9d9009e667027f221ee`
- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < ae88c8256547b63980770a9ea7be73a15900d27e`
- `Linux >= 4832c30d5458387ff2533ff66fbde26ad8bb5a2d < 2ffb4f5c2ccb2fa1c049dd11899aee7967deef5a`
- `Linux 4.14`

## Remediation

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