CVE-2026-9816
8.3
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H
Summary
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-2026-00685
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| Mattermost | Mattermost | 11.7.0 <= 11.7.6 | affected |
| Mattermost | Mattermost | 10.11.0 <= 10.11.21 | affected |
| Mattermost | Mattermost | 11.8.0 <= 11.8.3 | affected |
| Mattermost | Mattermost | 11.9.0 | unaffected |
| Mattermost | Mattermost | 11.7.7 | unaffected |
| Mattermost | Mattermost | 10.11.22 | unaffected |
| Mattermost | Mattermost | 11.8.4 | unaffected |
Weaknesses
- CWE-863: CWE-863: Incorrect Authorization
References
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