CVE-2026-8821
HIGH
7.1
Our Analysis: General Purpose
Our model has classified this vulnerability as relevant to General Purpose Systems, helping your team prioritize efforts effectively.
Published Date
September 14, 2026
Last Modified
September 14, 2026
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Description
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 fail to validate channel member-management permission during playbook run creation, allowing an authenticated channel member to add an arbitrary user to a restricted channel via the run owner field.. Mattermost Advisory ID: MMSA-2026-00677