---
id: CVE-2026-23083
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fou: Don't allow 0 for FOU_ATTR_IPPROTO.

  fou_udp_recv() has the same problem mentioned in the previous
  patch.

  If FOU_ATTR_IPPROTO is set to 0, skb is not freed by
  fou…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  fou: Don't allow 0 for FOU_ATTR_IPPROTO.

  fou_udp_recv() has the same problem mentioned in the previous
  patch.

  If FOU_ATTR_IPPROTO is set to 0, skb is not freed by
  fou…
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_kernel
affected:
  - 'linux_kernel >= 3.18, < 5.10.249'
  - 'linux_kernel >= 5.11, < 5.15.199'
  - 'linux_kernel >= 5.16, < 6.1.162'
  - 'linux_kernel >= 6.2, < 6.6.122'
  - 'linux_kernel >= 6.7, < 6.12.68'
  - 'linux_kernel >= 6.13, < 6.18.8'
  - linux_kernel = 6.19
patched:
  - linux_kernel 6.18.8
published: '2026-02-04'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:41.103'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-23083'
references:
  - url: 'https://git.kernel.org/stable/c/1cc98b8887cabb1808d2f4a37cd10a7be7574771'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/611ef4bd9c73d9e6d87bed57a635ff1fdd8c91ea'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6e983789b7588ee59cbf303583546c043bad8e19'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9b75dff8446ec871030d8daf5a69e74f5fe8b956'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b7db31a52c3862a1a32202a273a4c32e7f5f4823'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c7498f9bc390479ccfad7c7f2332237ff4945b03'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00154
epssPercentile: 0.04519
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-06-10T20:41:31.350182Z'
ingestedAt: '2026-09-08T15:33:26.994Z'
---

## Overview

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

fou: Don't allow 0 for FOU_ATTR_IPPROTO.

fou_udp_recv() has the same problem mentioned in the previous
patch.

If FOU_ATTR_IPPROTO is set to 0, skb is not freed by
fou_udp_recv() nor "resubmit"-ted in ip_protocol_deliver_rcu().

Let's forbid 0 for FOU_ATTR_IPPROTO.

## Affected

- `linux_kernel >= 3.18, < 5.10.249`
- `linux_kernel >= 5.11, < 5.15.199`
- `linux_kernel >= 5.16, < 6.1.162`
- `linux_kernel >= 6.2, < 6.6.122`
- `linux_kernel >= 6.7, < 6.12.68`
- `linux_kernel >= 6.13, < 6.18.8`
- `linux_kernel = 6.19`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.18.8`