---
id: CVE-2026-89564
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ip: orphan prefetched skbs before multicast forwarding

  IPv4 and IPv6 input preserve an skb->sk association installed by
  bpf_sk_assign() so that local delivery can use …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ip: orphan prefetched skbs before multicast forwarding

  IPv4 and IPv6 input preserve an skb->sk association installed by
  bpf_sk_assign() so that local delivery can use …
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'
cwe:
  - CWE-825
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 <
    e62aef7d6a5b27569bf540bbe11a9482117ff588
  - >-
    Linux >= cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 <
    a8af6fbac895f057c4b8ff8a2e3fb4c5827fe4ce
  - >-
    Linux >= cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 <
    f1281d4b99089fbaf0d3579bba62a814ebb4de4d
  - >-
    Linux >= cf7fbe660f2dbd738ab58aea8e9b0ca6ad232449 <
    e36ce6e78fe3fc3c071a26750783b7ba081ce10d
  - Linux 5.7
published: '2026-09-11'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T14:17:23.440'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89564'
references:
  - url: 'https://git.kernel.org/stable/c/a8af6fbac895f057c4b8ff8a2e3fb4c5827fe4ce'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e36ce6e78fe3fc3c071a26750783b7ba081ce10d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e62aef7d6a5b27569bf540bbe11a9482117ff588'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f1281d4b99089fbaf0d3579bba62a814ebb4de4d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89564.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89564'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532326'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89564'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89564'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89564.mbox
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00175
epssPercentile: 0.06141
scores:
  nvd: 7.8
  cna: 7.8
  vendor: 7
ingestedAt: '2026-09-14T15:23:07.474Z'
---

## Overview

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

ip: orphan prefetched skbs before multicast forwarding

IPv4 and IPv6 input preserve an skb->sk association installed by
bpf_sk_assign() so that local delivery can use the selected socket under
RCU. Both address families can also prefetch a socket in UDP early demux.
In both paths (BPF and UDP early demux) a reference is not guaranteed to
be held on the socket.

When a multicast packet is not locally deliverable, IPv6 hands the
original skb to ip6_mr_input(). IPv4's ip_mr_input() similarly keeps the
original skb when local delivery is not needed. Either path can put the
skb on an unresolved multicast route queue or forward it after the
receive-side RCU section ends.

After the prefetched socket is destroyed, a later skb free invokes
sock_pfree() and dereferences the stale skb->sk. Orphan the skb before
each non-local multicast forwarding path. Local delivery retains the
original skb; the existing skb_clone() calls provide multicast forwarding
with a socket-free clone.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4, Red Hat Enterprise Linux 6 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89564.json)