CVE-2026-6739

Mattermost: Delegated admins could patch protected default system roles

Published Jun 12, 2026 CVSS 3.1 · 6.7 Medium EPSS < 1% KEV · Not listed
Description
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656

Remediation

Vendor Solution

Update Mattermost to versions 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 or higher.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-m2w9-h2mm-79qr Mattermost doesn't require system-level permission when patching protected default system roles
References
History
Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Metrics ssvc

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

Type Values Removed Values Added
Description Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to require system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656
Title Mattermost: Delegated admins could patch protected default system roles
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 6.7, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Jun 13, 2026, 3:56 AM
Reserved
Apr 21, 2026, 8:47 AM
Status
Analyzed
Published
Jun 12, 2026, 5:16 PM
Modified
Jun 18, 2026, 2:35 PM