---
id: CVE-2026-10103
title: >-
  Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19
  fail to verify post ownership in the shared channel inbound sync handler,
  which allows an authenticated remote cluster to modify or delete posts
  authored by loca…
summary: >-
  Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19
  fail to verify post ownership in the shared channel inbound sync handler,
  which allows an authenticated remote cluster to modify or delete posts
  authored by loca…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-639
published: '2026-07-13'
updated: '2026-07-13'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-10103'
references:
  - url: 'https://mattermost.com/security-updates'
    label: responsibledisclosure@mattermost.com
tags:
  - nvd
ingestedAt: '2026-07-13T12:26:57.356Z'
epss: 0.00242
epssPercentile: 0.15618
---

## Overview

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to verify post ownership in the shared channel inbound sync handler, which allows an authenticated remote cluster to modify or delete posts authored by local users or other remotes via crafted sync messages referencing arbitrary post IDs in channels shared with that remote.. Mattermost Advisory ID: MMSA-2026-00689

## Remediation

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