CVE-2026-6689
Description
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Fail to enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation (the check was only applied on update/patch), which allows an authenticated user holding PermissionCreateTeam but not PermissionInviteUser on the resulting team to configure invite-controlled team settings (make the team publicly joinable via open invite and/or constrain membership via allowed domains) that they are not permitted to set on an existing team via POST /api/v4/teams with allow_open_invite: true and/or a non-empty allowed_domains in the request body.. Mattermost Advisory ID: MMSA-2026-00655
How to fix
- mattermost mattermost_server10.11.17, 11.5.5, 11.6.2 or later
- github.com/mattermost/mattermost-server11.6.1, 11.5.5, 10.11.17, 10.11.17+incompatible, 11.5.5+incompatible, 11.6.1+incompatible or later
- github.com/mattermost/mattermost/server/v88.0.0-20260501144115-7d6816abdfd1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| mattermost mattermost_server | 10.11.0 ≤ v < 10.11.17, 11.5.0 ≤ v < 11.5.5, 11.6.0 ≤ v < 11.6.2 | 10.11.17, 11.5.5, 11.6.2 |
| github.com/mattermost/mattermost-serverGo | 11.6.0 ≤ v < 11.6.1, 11.5.0 ≤ v < 11.5.5, 10.11.0 ≤ v < 10.11.17, 10.11.0+incompatible ≤ v < 10.11.17+incompatible, 11.5.0+incompatible ≤ v < 11.5.5+incompatible, 11.6.0+incompatible ≤ v < 11.6.1+incompatible | 11.6.1, 11.5.5, 10.11.17, 10.11.17+incompatible, 11.5.5+incompatible, 11.6.1+incompatible |
| github.com/mattermost/mattermost/server/v8Go | 8.0.0-20250731163400-5b955468ea1e ≤ v < 8.0.0-20260501144115-7d6816abdfd1 | 8.0.0-20260501144115-7d6816abdfd1 |
| github.com/mattermost/mattermost-server/v5Go | No range specified | — |
| github.com/mattermost/mattermost-server/v6Go | No range specified | — |
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