GHSA-wvcv-9xpm-7mqc Mattermost doesn't enforce slash command trigger-word uniqueness during command updates

• Go github.com/mattermost/mattermost/server/v8: >= 11.5.0, < 11.5.2 → fixed in 11.5.2 • Go github.com/mattermost/mattermost/server/v8: >= 10.11.0, < 10.11.14 → fixed in 10.11.14 • Go github.com/mattermost/mattermost/server/v8: >= 11.4.0, < 11.4.4 → fixed in 11.4.4 • Go github.com/mattermost/mattermost/server/v8: < 8.0.0-20260306123948-f5fe8ded6b63 → fixed in 8.0.0-20260306123948-f5fe8ded6b63 • Go github.com/mattermost/mattermost-server: < 5.3.2-0.20260306123948-f5fe8ded6b63 → fixed in 5.3.2-0.20260306123948-f5fe8ded6b63

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