Grub BootHole vulnerability patches cause mass denial of service. Affected systems include Ubuntu, Mint, Redhat, CentOS and others. Problem manifests upon reboot (or restart after a power outage etc) causes the system to become unbootable. Manual repair of the Grub bootloader is required. A bug in cloud-init is causing problems across major cloud providers with Grub, such as Digital Ocean and Azure, having the same impact: patched systems then fail to boot.”]