CVE-2026-16044

MediumCVSS 5.4

Published: 17/08/2026(UTC)Updated: 18/08/2026(UTC)Translated: 18/08/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.17%

7th percentile - higher than 7% of all known CVEs

Summary

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.

Risk Assessment

The risk includes privilege escalation for guest users, potentially leading to unauthorized administrative actions on boards.

Recommendation

Upgrade Mattermost to a version that fixes this vulnerability (as per vendor recommendations).

Original NVD description (English source)

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