I've read many forums and blogs and articles comparing OpenVZ, KVM and XEN. And I have seen many times that one of the negatives of OpenVZ is that its less secure. However, I have yet to see an explanation as to how and why it is less secure other than the fact that OpenVZ uses a shared kernel.
I assume that if the host is compromised for any of these virtualization technologies, the containers can easily be accessed. So from that perspective, they are the same.
Is it easier to break out of the OpenVZ container and gain access to the host/other containers?
Is there some other way that OpenVZ is less secure?