---
id: CVE-2026-82920
title: >-
  Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 fail
  to enforce authorization boundaries on the access control policy update
  endpoint which allows a channel or team administrator to detach a
  system-assigned ABAC …
summary: >-
  Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 fail
  to enforce authorization boundaries on the access control policy update
  endpoint which allows a channel or team administrator to detach a
  system-assigned ABAC …
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N'
cwe:
  - CWE-863
vendor: Mattermost
product: Mattermost
affected:
  - Mattermost >= 11.9.0 <= 11.9.0
  - Mattermost >= 11.8.0 <= 11.8.4
  - Mattermost >= 11.7.0 <= 11.7.7
published: '2026-09-14'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T19:30:49.967'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82920'
references:
  - url: 'https://mattermost.com/security-updates'
    label: responsibledisclosure@mattermost.com
tags:
  - nvd
  - cve.org
epss: 0.00255
epssPercentile: 0.15242
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-14T19:13:28.324125Z'
ingestedAt: '2026-09-14T15:23:07.422Z'
---

## Overview

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724

## Remediation

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