CVE-2026-26230
Received Received - Intake
Permission Validation Bypass in Mattermost Team Roles API

Publication date: 2026-03-16

Last updated on: 2026-03-18

Assigner: Mattermost, Inc.

Description
Mattermost versions 10.11.x <= 10.11.10 fail to properly validate permission requirements in the team member roles API endpoint which allows team administrators to demote members to guest role. Mattermost Advisory ID: MMSA-2025-00531
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Meta Information
Published
2026-03-16
Last Modified
2026-03-18
Generated
2026-06-16
AI Q&A
2026-03-16
EPSS Evaluated
2026-06-14
NVD
CVE-2026-26230
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
mattermost mattermost_server From 10.11.0 (inc) to 10.11.11 (exc)
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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 10.11.x up to and including 10.11.10. It occurs because the software fails to properly validate permission requirements in the team member roles API endpoint. This flaw allows team administrators to demote members to the guest role, which they might not be authorized to do.

Impact Analysis

The impact of this vulnerability is that team administrators could improperly change the roles of team members by demoting them to guest status. This could lead to unauthorized restriction of access or privileges for certain users within a Mattermost team, potentially disrupting collaboration or access to information.

Compliance Impact

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