A vulnerability in the update mechanism of Subaru StarLink Harman head units 2017, 2018, and 2019 may give an attacker (with physical access to the vehicle\'s USB ports) the ability to rewrite the firmware of the head unit. This occurs because the device accepts modified QNX6 filesystem images (as long as the attacker obtains access to certain Harman decryption/encryption code) as a consequence of a bug where unsigned images pass a validity check. An attacker could potentially install persistent malicious head unit firmware and execute arbitrary code as the root user.