Description
Mattermost Desktop App versions <=6.2 6.2.2.0 fail to validate the URL scheme when checking whether a target URL is internal to the connected server, which allows a network-positioned attacker to load a plugin popout window over an insecure connection via a link using a downgraded URL scheme. Mattermost Advisory ID: MMSA-2026-00717
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | ≤ 6.2.2 | 6.3.0 |
Advisories 1
- WID-SEC-2026-2876 Mattermost Desktop: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 17, 2026
References
- MMSA-2026-00717 vendor-advisory