Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when accessing channel information which allows guest users to discover active public channels and their metadata via the /api/v4/teams/{team_id}/channels/ids endpoint
{
"github_reviewed_at": "2025-10-16T20:54:54Z",
"nvd_published_at": "2025-10-16T08:15:35Z",
"cwe_ids": [
"CWE-862"
],
"severity": "MODERATE",
"github_reviewed": true
}