Kimai versions before 2.65.0 contain an authorization bypass vulnerability in the REST API timesheet collection endpoint that fails to enforce activity-team access controls. Users with view_other_timesheet permission can list timesheets using activities restricted to teams they do not belong to, bypassing intended data isolation.

Kimai (kimai/kimai) through 2.65.0 contains a business logic / improper authorization vulnerability in the default team creation endpoints. An authenticated user with project permission-management privileges can create or use a customer, project, or activity whose name matches an existing team; because the endpoints POST /api/customers/{id}/team, POST /api/projects/{id}/team, and POST /api/activities/{id}/team reuse an existing team of the same name and add the current user as teamlead without verifying that the user is authorized to manage that team, the attacker gains unauthorized team-lead (administration) rights over the existing team. Fixed in 2.65.0.

Kimai before 2.65.0 fails to properly validate permissions when removing team access to activities, projects, and customers via API endpoints. Authenticated users with edit_team permission can revoke team access without the required permissions_activity check, bypassing authorization controls.

Kimai before 2.63.0 contains an improper authorization vulnerability in team access endpoints that allows authenticated users with team edit permissions and read-only access to grant team access to customers, projects, or activities. Attackers can exploit insufficient permission checks by sending POST requests to team access endpoints to modify access control lists for entities they should not be able to modify.