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.