---
id: CVE-2026-97974
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv6: null-check fib6_node before accessing in __ip6_del_rt_siblings()

  syzbot reported a null-ptr-deref in __ip6_del_rt_siblings() [0].

  The stack trace hinted towards…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ipv6: null-check fib6_node before accessing in __ip6_del_rt_siblings()

  syzbot reported a null-ptr-deref in __ip6_del_rt_siblings() [0].

  The stack trace hinted towards…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= bd11ff421d36abdb585b9104fa70057bf01b3110 <
    e7ff91f19c1aae039a4257fa86fe849afe185291
  - >-
    Linux >= bd11ff421d36abdb585b9104fa70057bf01b3110 <
    1155234c2227cf36072a43e1e09119472ade7ca7
  - >-
    Linux >= bd11ff421d36abdb585b9104fa70057bf01b3110 <
    cdca92eddc025fdb90071be97738f7d55a65f8dd
  - Linux 6.16
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:25.310'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97974'
references:
  - url: 'https://git.kernel.org/stable/c/1155234c2227cf36072a43e1e09119472ade7ca7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cdca92eddc025fdb90071be97738f7d55a65f8dd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e7ff91f19c1aae039a4257fa86fe849afe185291'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.870Z'
---

## Overview

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

ipv6: null-check fib6_node before accessing in __ip6_del_rt_siblings()

syzbot reported a null-ptr-deref in __ip6_del_rt_siblings() [0].

The stack trace hinted towards a null dereference of rt->fib6_node when
fn->leaf is accessed in __ip6_del_rt_siblings(). With
RTNL_FLAG_DOIT_UNLOCKED set, inet6_rtm_delroute() operations run
concurrently without acquiring the RTNL lock. In ip6_route_del(), the
route lookup happens under rcu_read_lock() without acquiring
table->tb6_lock.

Between ip6_route_del() looking up the route and __ip6_del_rt_siblings()
acquiring table->tb6_lock, another thread can modify the routing table.
For example, when an ECMP route is replaced via RTM_NEWROUTE with
NLM_F_REPLACE, fib6_add_rt2node() unlinks all old siblings and sets
iter->fib6_node = NULL. A reproducer was found that triggers this [1].

Add a check to ensure rt->fib6_node is non-null before accessing it.

[0]
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
RIP: 0010:__ip6_del_rt_siblings+0x31e/0x7c0 net/ipv6/route.c:4056
Call Trace:
 <TASK>
 ip6_route_del+0x1054/0x1110 net/ipv6/route.c:4232
 inet6_rtm_delroute+0x5d7/0x6d0 net/ipv6/route.c:5669
 rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7132
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7f5/0x990 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800
 __sock_sendmsg net/socket.c:815 [inline]
 ____sys_sendmsg+0x565/0x870 net/socket.c:2713
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767
 __sys_sendmsg net/socket.c:2799 [inline]
 __do_sys_sendmsg net/socket.c:2804 [inline]
 __se_sys_sendmsg net/socket.c:2802 [inline]
 __x64_sys_sendmsg+0x1b7/0x290 net/socket.c:2802
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
 </TASK>

[1] https://gist.github.com/NamanGulati/0766a1159b6ca61928faaf87425ff899

## Remediation

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