---
id: CVE-2026-43198
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tcp: fix potential race in tcp_v6_syn_recv_sock()

  Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock()
  is done too late.

  After tcp_v4_syn_recv_sock…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  tcp: fix potential race in tcp_v6_syn_recv_sock()

  Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock()
  is done too late.

  After tcp_v4_syn_recv_sock…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-362
  - CWE-821
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.12.1, < 6.18.16'
  - 'linux_kernel >= 6.19, < 6.19.6'
  - linux_kernel = 2.6.12
  - linux_kernel = 7.0
patched:
  - linux_kernel 6.19.6
published: '2026-05-06'
updated: '2026-09-14'
sourceUpdated: '2026-09-14T12:17:40.837'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-43198'
references:
  - url: 'https://git.kernel.org/stable/c/7178e2a8027423b2af17ab95df73a749a5b72e5b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/858d2a4f67ff69e645a43487ef7ea7f28f06deae'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9ed654e340f4c73bc6f0af2fbc90ac293e645ce0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a7e761ba55efaa9c49e0afdd304bb78167af3429'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/aef4a9ae95d1bc4f7897065011e6261026719aeb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cd644e6dc72eec8d9d988717ea1c54f8668ded69'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dad1fe7db6c6519138430ac8f5e589c18f83bfc9'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fe89b2f05b854847784f91127319172945c1fadd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://access.redhat.com/errata/RHSA-2026:30129'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:33215'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:33285'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:34094'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:34443'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:35863'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:35894'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:35896'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:35904'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:36073'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:36216'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:36348'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:36349'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:41236'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-43198'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2467228'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43198.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
  - cve.org
epss: 0.00395
epssPercentile: 0.30935
ingestedAt: '2026-07-02T12:34:40.546Z'
---

## Overview

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

tcp: fix potential race in tcp_v6_syn_recv_sock()

Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock()
is done too late.

After tcp_v4_syn_recv_sock(), the child socket is already visible
from TCP ehash table and other cpus might use it.

Since newinet->pinet6 is still pointing to the listener ipv6_pinfo
bad things can happen as syzbot found.

Move the problematic code in tcp_v6_mapped_child_init()
and call this new helper from tcp_v4_syn_recv_sock() before
the ehash insertion.

This allows the removal of one tcp_sync_mss(), since
tcp_v4_syn_recv_sock() will call it with the correct
context.

## Affected

- `linux_kernel >= 2.6.12.1, < 6.18.16`
- `linux_kernel >= 6.19, < 6.19.6`
- `linux_kernel = 2.6.12`
- `linux_kernel = 7.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.19.6`