---
id: CVE-2026-89561
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()

  ipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL
  check when reading idev->cnf.rpl…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()

  ipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL
  check when reading idev->cnf.rpl…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-476
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <
    e7123e10c86eb88eaa90537dd1f232706de2d308
  - >-
    Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <
    63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c
  - >-
    Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <
    eab3a917cdcb182542a3aac6a0d2d30659ca9821
  - >-
    Linux >= 8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <
    f826df95332c07380206dbd54178b6eefb311aba
  - Linux 5.7
published: '2026-09-11'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T14:17:23.290'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89561'
references:
  - url: 'https://git.kernel.org/stable/c/63f50e9f90d0287ad66a0955ebfc2d3a9c044a1c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e7123e10c86eb88eaa90537dd1f232706de2d308'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/eab3a917cdcb182542a3aac6a0d2d30659ca9821'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f826df95332c07380206dbd54178b6eefb311aba'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89561.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89561'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532448'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89561'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89561'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89561.mbox
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.0063
epssPercentile: 0.4796
scores:
  nvd: 7.5
  cna: 7.5
  vendor: 5.5
ingestedAt: '2026-09-14T15:23:07.474Z'
---

## Overview

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

ipv6: rpl: fix NULL dereference of idev in ipv6_rpl_srh_rcv()

ipv6_rpl_srh_rcv() dereferences idev from __in6_dev_get() without a NULL
check when reading idev->cnf.rpl_seg_enabled.

When the device's MTU drops below IPV6_MIN_MTU, addrconf_ifdown() clears
dev->ip6_ptr through RCU_INIT_POINTER(). A packet that passed the idev
check in ip6_rcv_core() can then reach ipv6_rpl_srh_rcv() with
dev->ip6_ptr already NULL.

Reproduced by flooding the receiving interface with ping6 traffic while
flapping its MTU between 1500 and 1200:

 BUG: KASAN: null-ptr-deref in ipv6_rpl_srh_rcv+0xb3/0x1070
 Read of size 4 at addr 00000000000006b4 by task ping6/394

 CPU: 2 UID: 0 PID: 394 Comm: ping6 Not tainted 7.2.0-rc7-micro-vm-dev-00095-g24ef02f934ee #240 PREEMPT(full)
 Call Trace:
  <IRQ>
  kasan_report+0xc6/0x100
  ipv6_rpl_srh_rcv+0xb3/0x1070
  ip6_protocol_deliver_rcu+0x759/0x9a0
  ip6_input_finish+0xa8/0x1b0
  ip6_input+0xe1/0x490
  ipv6_rcv+0x33d/0x460
  __netif_receive_skb_one_core+0xd6/0x130
  process_backlog+0x2cc/0xa00
  __napi_poll.constprop.0+0x56/0x270
  net_rx_action+0x327/0x730
  handle_softirqs+0x11e/0x630
  do_softirq+0xb3/0xf0
  </IRQ>

Both ipv6_rpl_srh_rcv() and ipv6_srh_rcv() are called only from
ipv6_rthdr_rcv(), which already has an idev lookup.

Fix the NULL dereference on the RPL path by checking idev in
ipv6_rthdr_rcv(), before it calls either function. The callees take idev as
an argument and no longer call __in6_dev_get(), so the packet is now
dropped in one place, with SKB_DROP_REASON_IPV6DISABLED on both paths.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89561.json)