---
id: CVE-2026-80586
title: 'mptcp: options: reset DSS fields in case of unexpected size'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mptcp: options: reset DSS fields in case of unexpected size

  A remote peer could send a malformed DSS with a wrong size, followed by
  another DSS or MPC + Data. In this …
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'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    15e35fdad7a5576bf3f1c8d688877aeb5d1b506b
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    b1256090816ec46011601e084be580731df58fc7
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    192878df582c51d440bf7b91a15f297f29f2b596
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    26dac5c9ffb20812b475fdf253eb04fab99cff3b
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    4e80eff5c1c893aca2ac1d202f0b256d2e52ecde
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    1fade1b2ac5b1a4948e538fae7313bea57b5ac36
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    27ed642a4e7e4b5df4b8522c72c457a67e052493
  - >-
    Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 <
    35772b4981f38ba8059372cde8753e8e477e98ec
  - Linux 5.6
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T19:17:59.284912Z'
published: '2026-08-26'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:26:28.632Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80586'
references:
  - url: 'https://git.kernel.org/stable/c/15e35fdad7a5576bf3f1c8d688877aeb5d1b506b'
  - url: 'https://git.kernel.org/stable/c/b1256090816ec46011601e084be580731df58fc7'
  - url: 'https://git.kernel.org/stable/c/192878df582c51d440bf7b91a15f297f29f2b596'
  - url: 'https://git.kernel.org/stable/c/26dac5c9ffb20812b475fdf253eb04fab99cff3b'
  - url: 'https://git.kernel.org/stable/c/4e80eff5c1c893aca2ac1d202f0b256d2e52ecde'
  - url: 'https://git.kernel.org/stable/c/1fade1b2ac5b1a4948e538fae7313bea57b5ac36'
  - url: 'https://git.kernel.org/stable/c/27ed642a4e7e4b5df4b8522c72c457a67e052493'
  - url: 'https://git.kernel.org/stable/c/35772b4981f38ba8059372cde8753e8e477e98ec'
tags:
  - cve.org
epss: 0.00399
epssPercentile: 0.32548
ingestedAt: '2026-10-16T19:46:24.312Z'
---

## Overview

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

mptcp: options: reset DSS fields in case of unexpected size

A remote peer could send a malformed DSS with a wrong size, followed by
another DSS or MPC + Data. In this case, the first suboption will be
ignored, but leaving some fields written, which could lead to
inconsistency or access uninitialized data.

Explicitly reset the fields that could have been modified in case of
unexpected size.

## Affected

- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < 15e35fdad7a5576bf3f1c8d688877aeb5d1b506b`
- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < b1256090816ec46011601e084be580731df58fc7`
- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < 192878df582c51d440bf7b91a15f297f29f2b596`
- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < 26dac5c9ffb20812b475fdf253eb04fab99cff3b`
- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < 4e80eff5c1c893aca2ac1d202f0b256d2e52ecde`
- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < 1fade1b2ac5b1a4948e538fae7313bea57b5ac36`
- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < 27ed642a4e7e4b5df4b8522c72c457a67e052493`
- `Linux >= 648ef4b88673dadb8463bf0d4b10fbf33d55def8 < 35772b4981f38ba8059372cde8753e8e477e98ec`
- `Linux 5.6`

## Remediation

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