Vulnerability 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
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost Server | >= 10.11.0, < 10.11.17 |
Related Weaknesses (CWE)
References
- https://mattermost.com/security-updatesVendor Advisory
FAQ
What is CVE-2026-6689?
CVE-2026-6689 is a vulnerability with a CVSS score of 4.3 (MEDIUM). 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 creatio...
How severe is CVE-2026-6689?
CVE-2026-6689 has been rated MEDIUM with a CVSS base score of 4.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-6689?
Check the references section above for vendor advisories and patch information. Affected products include: Mattermost Mattermost Server.