Description
Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 Fail to validate channel ownership of an existing subscription before applying edits which allows an authenticated attacker to hijack subscriptions from channels they have no access to via a crafted PUT request to the subscription edit endpoint.. Mattermost Advisory ID: MMSA-2026-00650
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.7.0 – ≤ 11.7.0, 11.6.0 – ≤ 11.6.2, 11.5.0 – ≤ 11.5.5, 10.11.0 – ≤ 10.11.17 | 11.8.0 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Go | github.com/mattermost/mattermost-server | >= 11.7.0, < 11.7.1 | 11.7.1 | GHSA-mxq2-5jpg-7474 |
| Go | github.com/mattermost/mattermost-server | >= 11.6.0, < 11.6.3 | 11.6.3 | GHSA-mxq2-5jpg-7474 |
| Go | github.com/mattermost/mattermost-server | >= 11.5.0, < 11.5.6 | 11.5.6 | GHSA-mxq2-5jpg-7474 |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0, < 10.11.18 | 10.11.18 | GHSA-mxq2-5jpg-7474 |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0+incompatible, < 10.11.18+incompatible · >= 11.5.0+incompatible, < 11.5.6+incompatible · >= 11.6.0+incompatible, < 11.6.3+incompatible · >= 11.7.0+incompatible, < 11.7.1+incompatible | 10.11.18+incompatible, 11.5.6+incompatible, 11.6.3+incompatible, 11.7.1+incompatible | GO-2026-6484 |
Advisories 1
- WID-SEC-2026-1650 Mattermost (Desktop, Server und Mobile): Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 22, 2026
References
- MMSA-2026-00650 vendor-advisory