CVE-2026-82920

Published: Sep 14, 2026Modified: Oct 7, 2026

5.5

Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N

Exploitability: 2.3 / Impact: 2.7

Source: responsibledisclosure@mattermost.com (Secondary)

Description

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

Affected (3)

Products: Mattermost: Mattermost Server

Mattermost

1 product

Mattermost Server

Configuration A

3 vulnerable

Vulnerable Software	Affected Versions
Mattermost Mattermost Server	11.7.0 ≤ version < 11.7.8
Mattermost Mattermost Server	11.8.0 ≤ version < 11.8.5
Mattermost Mattermost Server	11.9.0 ≤ version < 11.9.1

Related CWEs

CWE-863

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.

References (1)

https://mattermost.com/security-updates

Source: responsibledisclosure@mattermost.com

Vendor Advisory

Timeline

No history available yet.