If you cannot open the guest session and get a VERR_NOT_FOUND VirtualBox error, follow the tips, solutions, and workarounds mentioned below. Check if “VBoxGuestAdditions.iso”n exists Insert Guest ...

It is the first thing you need to fix the issue as stated above. For that, you need to run the virtual machine showing the error and go to the Devices > Install Guest ...

Oracle has released patches for ten vulnerabilities in VirtualBox which allow attackers to break out of guest operating systems and attack the host operating system that VirtualBox runs on. Exploits ...