{"id":"CVE-2026-6689","aliases":["GHSA-c28q-m4gf-vg4q"],"title":"Mattermost doesn't enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation","summary":"Mattermost doesn't enforce PermissionInviteUser when setting AllowOpenInvite or AllowedDomains during team creation","severity":"medium","cvss":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N","vendor":"mattermost","product":"github.com/mattermost/mattermost-server","ecosystem":"go","affected":["github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1","github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5","github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17","github.com/mattermost/mattermost/server/v8 >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260501144115-7d6816abdfd1"],"patched":["github.com/mattermost/mattermost-server 11.6.1","github.com/mattermost/mattermost-server 11.5.5","github.com/mattermost/mattermost-server 10.11.17","github.com/mattermost/mattermost/server/v8 8.0.0-20260501144115-7d6816abdfd1"],"published":"2026-06-12","updated":"2026-08-24","source":"OSV","sourceUrl":"https://osv.dev/vulnerability/GHSA-c28q-m4gf-vg4q","references":[{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6689"},{"url":"https://github.com/mattermost/mattermost/pull/36402"},{"url":"https://github.com/mattermost/mattermost/pull/36384"},{"url":"https://github.com/mattermost/mattermost/pull/36383"},{"url":"https://github.com/mattermost/mattermost/pull/36375"},{"url":"https://github.com/mattermost/mattermost/pull/36188"},{"url":"https://github.com/mattermost/mattermost/commit/977c791e5b54bc14fdb96a2b3dacc85da5d8c623"},{"url":"https://github.com/mattermost/mattermost/commit/7d6816abdfd170169f717aea43c5716a1f9ef6b0"},{"url":"https://github.com/mattermost/mattermost/commit/479fc42d0ec6da48e76b59608233d90bfc69769d"},{"url":"https://github.com/mattermost/mattermost/commit/3a96344214b1a84df70d97052d46b6f2b40b0caa"},{"url":"https://github.com/mattermost/mattermost/commit/2dea05864024b3254fb28c5ed679592e2b7cd672"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v10.11.16"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.5.5"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.6.2"},{"url":"https://github.com/mattermost/mattermost/releases/tag/v11.7.0"},{"url":"https://mattermost.com/security-updates"},{"url":"https://github.com/mattermost/mattermost"}],"tags":["osv","go"],"epss":0.00152,"epssPercentile":0.04763,"ingestedAt":"2026-08-25T19:26:23.070Z","slug":"CVE-2026-6689","body":"## Overview\n\nMattermost 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\n\n## Affected packages\n\n- `github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1`\n- `github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5`\n- `github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17`\n- `github.com/mattermost/mattermost/server/v8 >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260501144115-7d6816abdfd1`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/mattermost/mattermost-server 11.6.1`\n- `github.com/mattermost/mattermost-server 11.5.5`\n- `github.com/mattermost/mattermost-server 10.11.17`\n- `github.com/mattermost/mattermost/server/v8 8.0.0-20260501144115-7d6816abdfd1`","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":23.7,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}