CVE-2026-16044: Insufficient validation of guest board admin privileges on archive import
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
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.9.0 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.7.7 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 10.11.22 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Patch MMSA-2026-00672
Event History
Frequently Asked Questions
What is the severity of CVE-2026-16044?
CVE-2026-16044 has a low severity score of 3.9.
How do I fix CVE-2026-16044?
To fix CVE-2026-16044, upgrade Mattermost to versions 11.7.7 or 10.11.22 or later.
What does CVE-2026-16044 affect?
CVE-2026-16044 affects Mattermost versions 11.7.x up to 11.7.6 and 10.11.x up to 10.11.21.
Can guest users gain elevated privileges due to CVE-2026-16044?
Yes, guest users can gain Board Admin privileges through a crafted .boardarchive file during board archive import.
What is the nature of the vulnerability in CVE-2026-16044?
CVE-2026-16044 involves insufficient validation of guest board admin privileges during board archive import.