virtualbox.org

If my virtual machine got infected by some virus, my host pc would be affected?
Translated from spanish to english by Google Translate

That depends on the circumstances, e.g. if you copied a virus infected executable file to a shared folder, then executed it on the host, then certainly the host could be affected. If you take sensible precautions then it's practically impossible. E.g. scan for viruses in the guest (resident antivirus is not required), and avoid leaving executable files in shared folders, even inside zips. Ignore the myths about JPEGs etc carrying viruses - only executable files matter.