CVE-2026-8823 PUBLISHED

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

Assigner: Mattermost
Reserved: 18.05.2026 Published: 22.06.2026 Updated: 22.06.2026

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

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L
CVSS Score: 3.8

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	High	Integrity Impact	Low
User Interaction	None	Availability Impact	Low

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.7.0 to 11.7.0 (incl.) affected from 10.11.0 to 10.11.17 (incl.) Version 11.8.0 is unaffected Version 11.7.1 is unaffected Version 10.11.18 is unaffected

Solutions

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

Credits

Edgar Bellot Micó finder

References

MMSA-2026-00669

Problem Types

CWE-863: Incorrect Authorization CWE