---
id: CVE-2026-74496
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fou: Fix use-after-free in fou_create()

  fou_create() publishes struct fou through sk_user_data before adding the
  new FOU port to the per-netns list
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fou: Fix use-after-free in fou_create()

  fou_create() publishes struct fou through sk_user_data before adding the
  new FOU port to the per-netns list.  If fou_add_to_por…
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 >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    58835985c035a8333742f829ad7e0889a082f9d3
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    9042867d4701728f0c6527215b11471759904d8f
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    a28d8903bfe76089ea4bbdbff9976965f9ef8107
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    b14361aca6350ff7907b0e9903c7b94dc7d5d4a0
  - Linux 3.18
published: '2026-08-15'
updated: '2026-09-21'
sourceUpdated: '2026-09-21T14:17:19.223'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74496'
references:
  - url: 'https://git.kernel.org/stable/c/58835985c035a8333742f829ad7e0889a082f9d3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9042867d4701728f0c6527215b11471759904d8f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a28d8903bfe76089ea4bbdbff9976965f9ef8107'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b14361aca6350ff7907b0e9903c7b94dc7d5d4a0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.0017
epssPercentile: 0.05569
ingestedAt: '2026-09-21T13:37:22.838Z'
---

## Overview

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

fou: Fix use-after-free in fou_create()

fou_create() publishes struct fou through sk_user_data before adding the
new FOU port to the per-netns list.  If fou_add_to_port_list() fails,
the error path frees fou while it is still reachable through
sk_user_data.  A concurrent receive can then dereference the freed
object in fou_from_sock().

This ordering issue was previously noted in the linked discussion.

The failure is reachable when local port 0 is requested.  Each socket
binds to a different ephemeral port, but fou_cfg_cmp() compares the
requested port 0 and reports -EALREADY once an entry already exists.

Release the tunnel socket before freeing fou so sk_user_data is cleared
first, and defer reclamation with kfree_rcu() to protect concurrent RCU
readers.  This matches the lifetime handling in fou_release().

## Remediation

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