medium4.3
CVE-2026-28732
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which …
Impact
Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to enforce slash command trigger-word uniqueness during command updates which allows an authenticated team member with Manage Own Slash Commands permission to hijack and impersonate existing system or custom slash commands via editing their own slash command trigger to an already-registered trigger through the command update API. Mattermost Advisory ID: MMSA-2026-00597
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/mattermost/mattermost/server/v8 | >= 11.5.0, < 11.5.2 | 11.5.2 |
| go | github.com/mattermost/mattermost-server | < 5.3.2-0.20260306123948-f5fe8ded6b63 | 5.3.2-0.20260306123948-f5fe8ded6b63 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Mattermost | Mattermost Server | from 10.11.0 before 10.11.14 from 11.4.0 before 11.4.4 from 11.5.0 before 11.5.2 |