---
id: CVE-2025-38552
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mptcp: plug races between subflow fail and subflow creation

  We have races similar to the one addressed by the previous patch between
  subflow failing and additional sub…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mptcp: plug races between subflow fail and subflow creation

  We have races similar to the one addressed by the previous patch between
  subflow failing and additional sub…
severity: critical
cvss: 9.4
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.15, < 6.1.149'
  - 'linux_kernel >= 6.2, < 6.6.101'
  - 'linux_kernel >= 6.7, < 6.12.40'
  - 'linux_kernel >= 6.13, < 6.15.8'
  - linux_kernel = 6.16
  - debian_linux = 11.0
patched:
  - linux_kernel 6.15.8
published: '2025-08-16'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:18:45.250'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-38552'
references:
  - url: 'https://git.kernel.org/stable/c/659da22dee5ff316ba63bdaeeac7b58b5442f6c2'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/7c96d519ee15a130842a6513530b4d20acd2bfcd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c476d627584b7589a134a8b48dd5c6639e4401c5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/def5b7b2643ebba696fc60ddf675dca13f073486'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f81b6fbe13c7fc413b5158cdffc6a59391a2a8db'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-032379.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00328
epssPercentile: 0.258
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-15T21:51:37.542339Z'
ingestedAt: '2026-10-15T22:48:25.511Z'
---

## Overview

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

mptcp: plug races between subflow fail and subflow creation

We have races similar to the one addressed by the previous patch between
subflow failing and additional subflow creation. They are just harder to
trigger.

The solution is similar. Use a separate flag to track the condition
'socket state prevent any additional subflow creation' protected by the
fallback lock.

The socket fallback makes such flag true, and also receiving or sending
an MP_FAIL option.

The field 'allow_infinite_fallback' is now always touched under the
relevant lock, we can drop the ONCE annotation on write.

## Affected

- `linux_kernel >= 5.15, < 6.1.149`
- `linux_kernel >= 6.2, < 6.6.101`
- `linux_kernel >= 6.7, < 6.12.40`
- `linux_kernel >= 6.13, < 6.15.8`
- `linux_kernel = 6.16`
- `debian_linux = 11.0`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.15.8`