medium5.9
CVE-2026-9571
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allow…
Impact
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated user or an attacker in possession of a valid refresh token to obtain new functional access tokens via the OAuth refresh token grant endpoint.. Mattermost Advisory ID: MMSA-2026-00680
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mattermost | Mattermost Server | from 10.11.0 before 10.11.20 from 11.6.0 before 11.6.5 from 11.7.0 before 11.7.3 |