Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when adding channel members which allows guest users to add any team members to their private channels via the `/api/v4/channels/{channel_id}/members` endpoint
| Package (Ecosystem) | Introduced | Fixed | Limit |
|---|---|---|---|
| github.com/mattermost/mattermost/server/v8(Go) | 0 | 8.0.0-20250820115038-ff30b84049f0 | N/A |
| github.com/mattermost/mattermost-server(Go) | 10.5.0 | 10.5.11 | N/A |
| github.com/mattermost/mattermost-server(Go) | 10.11.0 | 10.11.3 | N/A |
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