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

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Fixes

Solution

Update Mattermost to versions 11.8.0, 11.7.1, 10.11.18 or higher.


Workaround

No workaround given by the vendor.

References
History

Mon, 22 Jun 2026 20:15:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost

Mon, 22 Jun 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 22 Jun 2026 15:45:00 +0000

Type Values Removed Values Added
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
Title User Manager can demote bot accounts to guest without bot-management permission
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 3.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-06-22T16:12:31.350Z

Reserved: 2026-05-18T10:05:31.691Z

Link: CVE-2026-8823

cve-icon Vulnrichment

Updated: 2026-06-22T16:12:26.753Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-22T20:00:06Z

Weaknesses