---
id: CVE-2026-97568
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mptcp: syncookies: remember the request backup flag

  Instead of using an uninitialised bit when copying the info in
  subflow_ulp_clone().

  To fix this, no need to extend…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mptcp: syncookies: remember the request backup flag

  Instead of using an uninitialised bit when copying the info in
  subflow_ulp_clone().

  To fix this, no need to extend…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <
    61178d0b85b4b1b53e78b06e89d018d22d102f88
  - >-
    Linux >= efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <
    00b2bd518911e0daab00f4749cce68c191ccebb4
  - >-
    Linux >= efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <
    06d649f9cd03a9f8e768a658b20acf8d2c8022e0
  - >-
    Linux >= efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <
    b76c0e28b392620dfbaf92cdeedbf115820b44cb
  - Linux 1008f2bcbc8e461c1df3aebba30ac4f616ebe570
  - Linux 6f01f41b6a492ddf2da7609967cfaf57e7ca48a7
  - Linux 09176f80995105c62939728fbad5c437d61e7ff4
  - Linux 8ed3e34c766e8264d5d2e0436f86c51604d6a8a7
  - Linux 73e2baa301ee3f62ff971e68877adeb37f98cc67
  - Linux >= 5.10.224 < 5.11
  - Linux >= 5.15.165 < 5.16
  - Linux >= 6.1.104 < 6.2
  - Linux >= 6.6.45 < 6.7
  - Linux >= 6.10.4 < 6.11
  - Linux 6.11
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T11:17:07.453'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97568'
references:
  - url: 'https://git.kernel.org/stable/c/00b2bd518911e0daab00f4749cce68c191ccebb4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/06d649f9cd03a9f8e768a658b20acf8d2c8022e0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/61178d0b85b4b1b53e78b06e89d018d22d102f88'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b76c0e28b392620dfbaf92cdeedbf115820b44cb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.912Z'
---

## Overview

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

mptcp: syncookies: remember the request backup flag

Instead of using an uninitialised bit when copying the info in
subflow_ulp_clone().

To fix this, no need to extend the join_entry structure: backup is
coming from struct mptcp_subflow_request_sock, only one bit. Do the same
here by using one bit for both.

## Remediation

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