CVE-2026-8823
Received Received - Intake
Bot Account Privilege Degradation in Mattermost

Publication date: 2026-06-22

Last updated on: 2026-06-22

Assigner: Mattermost, Inc.

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
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Meta Information
Published
2026-06-22
Last Modified
2026-06-22
Generated
2026-06-22
AI Q&A
2026-06-22
EPSS Evaluated
N/A
NVD
CVE-2026-8823
EUVD
EUVD-2026-38276
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
mattermost mattermost to 11.7.0 (inc)
mattermost mattermost to 10.11.17 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-863 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.
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Executive Summary

This vulnerability exists in Mattermost versions 11.7.x up to 11.7.0 and 10.11.x up to 10.11.17. It occurs because the software fails to properly validate bot targets when demoting users to guests. This flaw allows a lower-privileged administrator to degrade arbitrary bot accounts by using the standard demote-user API.

Impact Analysis

The impact of this vulnerability is that a lower-privileged administrator can reduce the privileges or degrade bot accounts that they should not have control over. This could lead to disruption of automated processes or integrations that rely on these bot accounts, potentially affecting the integrity and availability of services within the Mattermost environment.

Mitigation Strategies

To mitigate this vulnerability, you should update Mattermost to a version later than 11.7.0 or 10.11.17 where the issue has been fixed.

Monitor Mattermost security updates and advisories regularly to apply patches promptly.

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