CVE-2026-9816
EUVD-2026-6054017.08.2026, 22:17
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate BoardMember.Scheme* fields server-side on insert and archive-import paths which allows a board editor or non-guest team member to grant board admin to arbitrary users via POST /api/v2/boards/{boardID}/members and POST /api/v2/teams/{teamID}/archive/import.. Mattermost Advisory ID: MMSA-2026-00685EnginsightAffected Products (NVD)
| Vendor | Product | Version |
|---|---|---|
| mattermost | mattermost_server | 10.11.0 ≤ 𝑥 < 10.11.22 |
| mattermost | mattermost_server | 11.7.0 ≤ 𝑥 < 11.7.7 |
| mattermost | mattermost_server | 11.8.0 ≤ 𝑥 < 11.8.4 |
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
| Vendor | Product | Version | Source |
|---|---|---|---|
| mattermost | mattermost | 11.7.0 ≤ 𝑥 ≤ 11.7.6 | CNA |
| mattermost | mattermost | 10.11.0 ≤ 𝑥 ≤ 10.11.21 | CNA |
| mattermost | mattermost | 11.8.0 ≤ 𝑥 ≤ 11.8.3 | CNA |
References