There was the secure golden key boot exploit last year[0]. In the conclusion they also points out that Microsoft can't revoke the affected bootmgr versions: >

There was the secure golden key boot exploit last year[0]. In the conclusion they also points out that Microsoft can't revoke the affected bootmgr versions: > Either way, it'd be impossible in practise for MS to revoke every bootmgr earlier than a certain point, as they'd break install media, recovery partitions, backups, etc. [0]: https://rol.im/securegoldenkeyboot/ https://rol.im/securegoldenkeyboot/