---
id: CVE-2026-89563
title: 'kernel: ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit() (CVE-2026-89563)'
summary: >-
  A flaw was found in the `ip6_tunnel` module of the Linux kernel. Incorrect
  handling of socket buffers (skb) during headroom reallocation in the
  `ip6_tnl_xmit()` function can lead to a double-free vulnerability. This occurs
  when an error pa…
severity: high
cvss: 7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: vendor
cwe: CWE-1341
vendor: Red Hat
product: Red Hat Enterprise Linux 9
affected:
  - enterprise_linux 10
  - enterprise_linux 8
  - enterprise_linux 9
  - openshift_container_platform 4
  - enterprise_linux 6
published: '2026-09-11'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T22:00:45+00:00'
source: CSAF
sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89563.json'
references:
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89563.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-89563'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532305'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-89563'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89563'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89563.mbox
  - url: 'https://git.kernel.org/stable/c/6e8eff8ed13b14708bc39f170144eacde494aac6'
  - url: 'https://git.kernel.org/stable/c/dc1a319a4815c074914e2812e0e9cd0164ca682b'
  - url: 'https://git.kernel.org/stable/c/629d5557e635cdbc109a14ed913ba5a540e3f79a'
  - url: 'https://git.kernel.org/stable/c/defa0adeff132cc90ed66915b9a104d9393e1e54'
  - url: 'https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74'
  - url: 'https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461'
  - url: 'https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52'
  - url: 'https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade'
tags:
  - csaf
  - vex
  - red-hat
  - cve.org
epss: 0.00176
epssPercentile: 0.06304
scores:
  vendor: 7
  cna: 7.8
ingestedAt: '2026-09-14T15:23:07.451Z'
---

## Overview

A flaw was found in the `ip6_tunnel` module of the Linux kernel. Incorrect handling of socket buffers (skb) during headroom reallocation in the `ip6_tnl_xmit()` function can lead to a double-free vulnerability. This occurs when an error path is taken after the original skb has been consumed, but the caller still holds a pointer to it, potentially allowing the same memory to be freed twice. This memory corruption issue could lead to a denial of service or potentially arbitrary code execution.

## 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 2026-09-18 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89563.json)

**kernel: ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()** — rated Important by Red Hat. Released 2026-09-11, updated 2026-09-18.

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

Not affected:

- Red Hat Enterprise Linux 7

## Remediation

Affected