---
id: CVE-2026-9602
title: >-
  Mattermost Desktop App versions <=6.2 6.0.2 5.6.13.0 fail to validate payloads
  sent from the Mattermost Web App to the Desktop App which allows a malicious
  server owner to crash the Mattermost Desktop App via changing the payload of a
  me…
summary: >-
  Mattermost Desktop App versions <=6.2 6.0.2 5.6.13.0 fail to validate payloads
  sent from the Mattermost Web App to the Desktop App which allows a malicious
  server owner to crash the Mattermost Desktop App via changing the payload of a
  me…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
vendor: mattermost
product: mattermost_desktop
affected:
  - mattermost_desktop < 5.13.7
  - 'mattermost_desktop >= 6.0.0, <= 6.0.2'
  - 'mattermost_desktop >= 6.2.0, < 6.2.1'
patched:
  - mattermost_desktop 6.2.1
published: '2026-07-17'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T13:32:07.993'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-9602'
references:
  - url: 'https://mattermost.com/security-updates'
    label: responsibledisclosure@mattermost.com
tags:
  - nvd
epss: 0.0042
epssPercentile: 0.3473
ingestedAt: '2026-10-15T14:07:30.098Z'
---

## Overview

Mattermost Desktop App versions <=6.2 6.0.2 5.6.13.0 fail to validate payloads sent from the Mattermost Web App to the Desktop App which allows a malicious server owner to crash the Mattermost Desktop App via changing the payload of a method to a malformed one. Mattermost Advisory ID: MMSA-2026-00678

## Affected

- `mattermost_desktop < 5.13.7`
- `mattermost_desktop >= 6.0.0, <= 6.0.2`
- `mattermost_desktop >= 6.2.0, < 6.2.1`

## Remediation

Upgrade past the affected range:

- `mattermost_desktop 6.2.1`