---
id: CVE-2023-53619
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: conntrack: Avoid nf_ct_helper_hash uses after free

  If nf_conntrack_init_start() fails (for example due to a
  register_nf_conntrack_bpf() failure), the nf_con…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: conntrack: Avoid nf_ct_helper_hash uses after free

  If nf_conntrack_init_start() fails (for example due to a
  register_nf_conntrack_bpf() failure), the nf_con…
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'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 3.6, < 4.14.322'
  - 'linux_kernel >= 4.15, < 4.19.291'
  - 'linux_kernel >= 4.20, < 5.4.251'
  - 'linux_kernel >= 5.5, < 5.10.188'
  - 'linux_kernel >= 5.11, < 5.15.121'
  - 'linux_kernel >= 5.16, < 6.1.39'
  - 'linux_kernel >= 6.2, < 6.4.4'
  - linux_kernel = 6.5
patched:
  - linux_kernel 6.4.4
published: '2025-10-07'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:17:44.370'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2023-53619'
references:
  - url: 'https://git.kernel.org/stable/c/00716f25f9697d02a0d9bd622575c7c7321ba3d0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/05561f822f27b9fa88fa5504ddec34bf38833034'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/4ee69c91cb8f9ca144bc0861969e5a1a3c6152a7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/61c7a5256543ae7d24cd9d21853d514c8632e1e9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6eef7a2b933885a17679eb8ed0796ddf0ee5309b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6f03ce2f1abcb9f9d0511e3659ca6eb60e39f566'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8289d422f5e484efe4a565fe18e862ecd621c175'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fce5cc7cbd4b92f979bf02c9ec5fb69aaeba92d7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.0022
epssPercentile: 0.12412
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-15T21:35:57.896822Z'
ingestedAt: '2026-10-15T22:48:25.411Z'
---

## Overview

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

netfilter: conntrack: Avoid nf_ct_helper_hash uses after free

If nf_conntrack_init_start() fails (for example due to a
register_nf_conntrack_bpf() failure), the nf_conntrack_helper_fini()
clean-up path frees the nf_ct_helper_hash map.

When built with NF_CONNTRACK=y, further netfilter modules (e.g:
netfilter_conntrack_ftp) can still be loaded and call
nf_conntrack_helpers_register(), independently of whether nf_conntrack
initialized correctly. This accesses the nf_ct_helper_hash dangling
pointer and causes a uaf, possibly leading to random memory corruption.

This patch guards nf_conntrack_helper_register() from accessing a freed
or uninitialized nf_ct_helper_hash pointer and fixes possible
uses-after-free when loading a conntrack module.

## Affected

- `linux_kernel >= 3.6, < 4.14.322`
- `linux_kernel >= 4.15, < 4.19.291`
- `linux_kernel >= 4.20, < 5.4.251`
- `linux_kernel >= 5.5, < 5.10.188`
- `linux_kernel >= 5.11, < 5.15.121`
- `linux_kernel >= 5.16, < 6.1.39`
- `linux_kernel >= 6.2, < 6.4.4`
- `linux_kernel = 6.5`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.4.4`