---
id: CVE-2026-23231
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nf_tables: fix use-after-free in nf_tables_addchain()

  nf_tables_addchain() publishes the chain to table->chains via
  list_add_tail_rcu() (in nft_chain_add())…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  netfilter: nf_tables: fix use-after-free in nf_tables_addchain()

  nf_tables_addchain() publishes the chain to table->chains via
  list_add_tail_rcu() (in nft_chain_add())…
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 >= 3.16, < 6.1.165'
  - 'linux_kernel >= 6.2, < 6.6.128'
  - 'linux_kernel >= 6.7, < 6.12.75'
  - 'linux_kernel >= 6.13, < 6.18.14'
  - 'linux_kernel >= 6.19, < 6.19.4'
patched:
  - linux_kernel 6.19.4
published: '2026-03-04'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:43.953'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-23231'
references:
  - url: 'https://git.kernel.org/stable/c/2a6586ecfa4ce1413daaafee250d2590e05f1a33'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2f9a4ffeb763aec822f8ff3d1e82202d27d46d4b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7017745068a9068904e1e7a1b170a5785647cc81'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/71e99ee20fc3f662555118cf1159443250647533'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dbd0af8083dd201f07c49110b2ee93710abdff28'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f3fe58ce37926a10115ede527d59b91bcc05400a'
    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-082556.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-253495.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-784472.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - exploit-available
  - cve.org
epss: 0.0103
epssPercentile: 0.63549
exploits:
  exploitdb: true
  checkedAt: '2026-10-27T17:02:44.815Z'
exploitAvailable: true
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-06-16T20:18:23.569815Z'
ingestedAt: '2026-09-08T15:33:26.993Z'
---

## Overview

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

netfilter: nf_tables: fix use-after-free in nf_tables_addchain()

nf_tables_addchain() publishes the chain to table->chains via
list_add_tail_rcu() (in nft_chain_add()) before registering hooks.
If nf_tables_register_hook() then fails, the error path calls
nft_chain_del() (list_del_rcu()) followed by nf_tables_chain_destroy()
with no RCU grace period in between.

This creates two use-after-free conditions:

 1) Control-plane: nf_tables_dump_chains() traverses table->chains
    under rcu_read_lock(). A concurrent dump can still be walking
    the chain when the error path frees it.

 2) Packet path: for NFPROTO_INET, nf_register_net_hook() briefly
    installs the IPv4 hook before IPv6 registration fails.  Packets
    entering nft_do_chain() via the transient IPv4 hook can still be
    dereferencing chain->blob_gen_X when the error path frees the
    chain.

Add synchronize_rcu() between nft_chain_del() and the chain destroy
so that all RCU readers -- both dump threads and in-flight packet
evaluation -- have finished before the chain is freed.

## Affected

- `linux_kernel >= 3.16, < 6.1.165`
- `linux_kernel >= 6.2, < 6.6.128`
- `linux_kernel >= 6.7, < 6.12.75`
- `linux_kernel >= 6.13, < 6.18.14`
- `linux_kernel >= 6.19, < 6.19.4`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.4`