---
id: CVE-2026-23083
title: 'fou: Don''t allow 0 for FOU_ATTR_IPPROTO.'
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: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    c7498f9bc390479ccfad7c7f2332237ff4945b03
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    611ef4bd9c73d9e6d87bed57a635ff1fdd8c91ea
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    6e983789b7588ee59cbf303583546c043bad8e19
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    1cc98b8887cabb1808d2f4a37cd10a7be7574771
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    b7db31a52c3862a1a32202a273a4c32e7f5f4823
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    9b75dff8446ec871030d8daf5a69e74f5fe8b956
  - >-
    Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 <
    7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5
  - Linux 3.18
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-06-10T20:41:31.350182Z'
published: '2026-02-04'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T08:44:46.514Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-23083'
references:
  - url: 'https://git.kernel.org/stable/c/c7498f9bc390479ccfad7c7f2332237ff4945b03'
  - url: 'https://git.kernel.org/stable/c/611ef4bd9c73d9e6d87bed57a635ff1fdd8c91ea'
  - url: 'https://git.kernel.org/stable/c/6e983789b7588ee59cbf303583546c043bad8e19'
  - url: 'https://git.kernel.org/stable/c/1cc98b8887cabb1808d2f4a37cd10a7be7574771'
  - url: 'https://git.kernel.org/stable/c/b7db31a52c3862a1a32202a273a4c32e7f5f4823'
  - url: 'https://git.kernel.org/stable/c/9b75dff8446ec871030d8daf5a69e74f5fe8b956'
  - url: 'https://git.kernel.org/stable/c/7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5'
tags:
  - cve.org
epss: 0.00137
epssPercentile: 0.02528
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 >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 < c7498f9bc390479ccfad7c7f2332237ff4945b03`
- `Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 < 611ef4bd9c73d9e6d87bed57a635ff1fdd8c91ea`
- `Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 < 6e983789b7588ee59cbf303583546c043bad8e19`
- `Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 < 1cc98b8887cabb1808d2f4a37cd10a7be7574771`
- `Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 < b7db31a52c3862a1a32202a273a4c32e7f5f4823`
- `Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 < 9b75dff8446ec871030d8daf5a69e74f5fe8b956`
- `Linux >= 23461551c00628c3f3fe9cf837bf53cf8f212b63 < 7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5`
- `Linux 3.18`

## Remediation

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