---
id: CVE-2026-9708
title: >-
  Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19
  fail to validate that an assigned incoming webhook user has access to the
  target team or channel, which allows a requester with webhook management
  permissions to…
summary: >-
  Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19
  fail to validate that an assigned incoming webhook user has access to the
  target team or channel, which allows a requester with webhook management
  permissions to…
severity: medium
cvss: 4.9
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N'
cwe:
  - CWE-639
published: '2026-07-13'
updated: '2026-07-13'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-9708'
references:
  - url: 'https://mattermost.com/security-updates'
    label: responsibledisclosure@mattermost.com
tags:
  - nvd
ingestedAt: '2026-07-13T12:26:58.193Z'
epss: 0.00361
epssPercentile: 0.29877
---

## Overview

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683

## Remediation

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