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

Project Subscriptions

Vendors Products
Mattermost Subscribe
Mattermost Subscribe
Advisories

No advisories yet.

Fixes

Solution

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


Workaround

No workaround given by the vendor.

References
History

Mon, 17 Aug 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Mon, 17 Aug 2026 15:45:00 +0000

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost

Mon, 17 Aug 2026 14:45:00 +0000

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'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: Mattermost

Published:

Updated: 2026-08-17T15:25:51.740Z

Reserved: 2026-07-17T09:40:22.350Z

Link: CVE-2026-16044

cve-icon Vulnrichment

Updated: 2026-08-17T15:25:47.520Z

cve-icon NVD

Status : Received

Published: 2026-08-17T15:16:53.857

Modified: 2026-08-17T16:16:50.460

Link: CVE-2026-16044

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-17T15:30:06Z

Weaknesses