---
id: CVE-2023-39189
title: A flaw was found in the Netfilter subsystem in the Linux kernel
summary: >-
  A flaw was found in the Netfilter subsystem in the Linux kernel. The
  nfnl_osf_add_callback function did not validate the user mode controlled
  opt_num field. This flaw allows a local privileged (CAP_NET_ADMIN) attacker to
  trigger an out-o…
severity: medium
cvss: 5.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:L'
cwe:
  - CWE-125
vendor: linux
product: linux_kernel
affected:
  - linux_kernel < 6.6
  - enterprise_linux = 8.0
  - enterprise_linux = 9.0
  - fedora = 38
patched:
  - linux_kernel 6.6
published: '2023-10-09'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T00:16:35.363'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-39189'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2024:2394'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2024:2950'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2024:3138'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/security/cve/CVE-2023-39189'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2226777'
    label: secalert@redhat.com
  - url: 'https://access.redhat.com/errata/RHSA-2024:2394'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://access.redhat.com/errata/RHSA-2024:2950'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://access.redhat.com/errata/RHSA-2024:3138'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://access.redhat.com/security/cve/CVE-2023-39189'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2226777'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-794697.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00402
epssPercentile: 0.32817
ingestedAt: '2026-10-15T01:08:04.209Z'
---

## Overview

A flaw was found in the Netfilter subsystem in the Linux kernel. The nfnl_osf_add_callback function did not validate the user mode controlled opt_num field. This flaw allows a local privileged (CAP_NET_ADMIN) attacker to trigger an out-of-bounds read, leading to a crash or information disclosure.

## Affected

- `linux_kernel < 6.6`
- `enterprise_linux = 8.0`
- `enterprise_linux = 9.0`
- `fedora = 38`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.6`