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 allowed_domains in the request body.. Mattermost Advisory ID: MMSA-2026-00655
{
"cna_assigner": "Mattermost",
"cwe_ids": [
"CWE-862"
],
"unresolved_ranges": [
{
"source": "AFFECTED_FIELD",
"extracted_events": [
{
"introduced": "11.6.0"
},
{
"last_affected": "11.6.1"
},
{
"introduced": "11.5.0"
},
{
"last_affected": "11.5.4"
},
{
"introduced": "10.11.0"
},
{
"last_affected": "10.11.15"
},
{
"introduced": "10.11.0"
},
{
"last_affected": "10.11.16"
}
]
}
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/6xxx/CVE-2026-6689.json"
}{
"source": "CPE_RANGE",
"cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"extracted_events": [
{
"introduced": "10.11.0"
},
{
"fixed": "10.11.17"
},
{
"introduced": "11.5.0"
},
{
"fixed": "11.5.5"
},
{
"introduced": "11.6.0"
},
{
"fixed": "11.6.2"
}
]
}