[a1xndr]

> VM escapes are pretty difficult, especially with modern, patched microcode processors

Most VM escapes happen through buggy virtual-devices written in C/C++/.. code. Virtual-device bugs that are exploitable by attackers with root access in the VM are found frequently.

[fsflover]

It's not frequent at all with Qubes hardware virtualization: https://www.qubes-os.org/security/xsa/.