Fleet's team maintainer can transfer hosts from any team via missing source team authorization

Fleet is open source device management software. Prior to 4.81.1, a broken access control vulnerability in Fleet's host transfer API allows a team maintainer to transfer hosts from any team into their own team, bypassing team isolation boundaries. Once transferred, the attacker gains full control over the stolen hosts, including the ability to execute scripts with root privileges. Version 4.81.1 patches the issue.