CVE-2026-6689: *Missing* {{invite_user}} *permission check on team creation allows unprivileged users to set open-invite and allowed-domains team settings*
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 allowopeninvite: true and/or a non-empty alloweddomains in the request body.. Mattermost Advisory ID: MMSA-2026-00655
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.7.0 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.6.2 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 11.5.5 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 10.11.16 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Fixed in 10.11.17 - Upgrade
Upgrade
Mattermostto a version that resolves this vulnerability.Patch MMSA-2026-00655
Event History
Frequently Asked Questions
What is the severity of CVE-2026-6689?
The severity of CVE-2026-6689 is medium with a score of 4.3.
How do I fix CVE-2026-6689?
To fix CVE-2026-6689, update Mattermost to versions 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 or higher.
What type of users are affected by CVE-2026-6689?
CVE-2026-6689 affects unprivileged users who can set open-invite and allowed-domains team settings.
What vulnerability does CVE-2026-6689 exploit?
CVE-2026-6689 exploits the missing PermissionInviteUser check during team creation.
Which Mattermost versions are vulnerable to CVE-2026-6689?
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, and 10.11.x <= 10.11.15 are vulnerable to CVE-2026-6689.