CVE-2026-8823

LOW

User Manager can demote bot accounts to guest without bot-management permission

Title source: cna
STIX 2.1

Description

Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669

References (1)

Core 1
Core References
Vendor Advisory vendor-advisory
MMSA-2026-00669
https://mattermost.com/security-updates

Scores

CVSS v3 3.8
EPSS 0.0023
EPSS Percentile 13.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-863
Status published
Products (6)
Mattermost/Mattermost 10.11.0 - 10.11.17
Mattermost/Mattermost 10.11.18
Mattermost/Mattermost 11.7.0
Mattermost/Mattermost 11.7.1
Mattermost/Mattermost 11.8.0
mattermost/mattermost_server 10.11.0 - 10.11.18
Published Jun 22, 2026
Tracked Since Jun 22, 2026