Description
Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to require re-entry of the stored client secret when validating an outgoing OAuth connection, which allows an authenticated user with permission to manage outgoing OAuth connections to obtain the secret via pointing the token URL at an attacker-controlled endpoint and triggering validation.. Mattermost Advisory ID: MMSA-2026-00761
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.9.0 – ≤ 11.9.1, 11.8.0 – ≤ 11.8.5, 11.7.0 – ≤ 11.7.10, 11.10.0 – ≤ 11.10.1 | 11.11.0 |
Advisories 1
- WID-SEC-2026-4009 Mattermost: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 15, 2026
References
- MMSA-2026-00761 vendor-advisory