CVE-2026-16044

Insufficient validation of guest board admin privileges on archive import

Published Aug 17, 2026 CVSS 3.1 · 3.9 Low EPSS < 1% KEV · Not listed
Description
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672

Remediation

Vendor Solution

Update Mattermost to versions 11.9.0, 11.7.7, 10.11.22 or higher.

Tracking

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Advisories

No advisories available
References
History
Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server
Type Values Removed Values Added
Metrics ssvc

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

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Description Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21 fail to prevent guest users from receiving Board Admin privileges during board archive import which allows a board member to escalate a guest user to Board Admin via importing a crafted .boardarchive file. Mattermost Advisory ID: MMSA-2026-00672
Title Insufficient validation of guest board admin privileges on archive import
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 3.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Aug 17, 2026, 3:25 PM
Reserved
Jul 17, 2026, 9:40 AM
Status
Analyzed
Published
Aug 17, 2026, 3:16 PM
Modified
Aug 18, 2026, 8:27 PM