Medium · published September 15, 2026
Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7, 10.11.x <= 10.11.22 Fail to sanitize Team objects returned by the data retention teams endpoint which allows an authenticated user holding only the read-only Data Retention Policy permission to obtain a private team's secret invite_id and email, and use it to join the team without authorization, via GET /api/v4/data_retention/policies/{policy_id}/teams.. Mattermost Advisory ID: MMSA-2026-00702
| Product | Versions | Fixed in |
|---|---|---|
| mattermost/mattermost_server | ≥ 10.11.0, < 10.11.23 | 10.11.23 |
| mattermost/mattermost_server | ≥ 11.7.0, < 11.7.8 | 11.7.8 |
| mattermost/mattermost_server | ≥ 11.8.0, < 11.8.5 | 11.8.5 |
| mattermost/mattermost_server | ≥ 11.9.0, < 11.9.1 | 11.9.1 |