Description
Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.7.0 – ≤ 11.7.0, 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-xmfh-3ccg-c9fx |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0, < 10.11.18 | 10.11.18 | GHSA-xmfh-3ccg-c9fx |
| Go | github.com/mattermost/mattermost-server | >= 10.11.0+incompatible, < 10.11.18+incompatible · >= 11.7.0+incompatible, < 11.7.1+incompatible | 10.11.18+incompatible, 11.7.1+incompatible | GO-2026-6547 |
| Go | github.com/mattermost/mattermost-server/v5 | all versions | — | GO-2026-6547 |
| Go | github.com/mattermost/mattermost-server/v6 | all versions | — | GO-2026-6547 |
| Go | github.com/mattermost/mattermost/server/v8 | < 8.0.0-20260518160100-9bd77d3fc4d2 | 8.0.0-20260518160100-9bd77d3fc4d2 | GHSA-xmfh-3ccg-c9fx |
References
- MMSA-2026-00669 vendor-advisory