---
id: CVE-2026-90111
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ip6mr: do not clone dst in ip6mr_cache_report()

  IPv6 input attaches a non-refcounted (NOREF) dst to skbs under RCU.
  When an ingress multicast packet misses MFC lookup,…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ip6mr: do not clone dst in ip6mr_cache_report()

  IPv6 input attaches a non-refcounted (NOREF) dst to skbs under RCU.
  When an ingress multicast packet misses MFC lookup,…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 67f415dd29063a5906c560051c00e42dcf01a4dd <
    4a674afaae4136c71943aa3e35d433676fd40e8f
  - >-
    Linux >= 67f415dd29063a5906c560051c00e42dcf01a4dd <
    235b42b5860189eb8c27c36435ad932cae65a734
  - Linux 5.3
published: '2026-09-17'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T18:17:42.500'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-90111'
references:
  - url: 'https://git.kernel.org/stable/c/235b42b5860189eb8c27c36435ad932cae65a734'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4a674afaae4136c71943aa3e35d433676fd40e8f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.00165
epssPercentile: 0.05032
ingestedAt: '2026-09-17T16:21:47.887Z'
---

## Overview

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

ip6mr: do not clone dst in ip6mr_cache_report()

IPv6 input attaches a non-refcounted (NOREF) dst to skbs under RCU.
When an ingress multicast packet misses MFC lookup,
ip6mr_cache_unresolved() places the skb onto the unresolved queue,
escaping the receive-side RCU grace period.

If the underlying route is deleted and freed, and the MFC queue is later
resolved with a wrong parent interface, ip6_mr_forward() invokes
ip6mr_cache_report(..., MRT6MSG_WRONGMIF), which executes
dst_clone(skb_dst(pkt)) on the freed dst entry, triggering a slab
use-after-free.

Report packets queued to mroute6_sk (a raw socket) and netlink
notifications do not require an attached dst entry.

Fix this by:
1. Removing dst_clone() in ip6mr_cache_report() and ensuring report skbs
   do not hold a dst.
2. Dropping skb_dst before queuing unresolved skbs in
   ip6mr_cache_unresolved(), matching the fact that multicast
   forwarding resolves outgoing routes anew via ip6_route_output().

## Remediation

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