Comment # 14 on bug 1175320 from Thorsten Kukuk

The biggest problem here is:
We use QXL and USB redirection by default. So currently, you cannot even
install a new VM! Without enabling changing of default values and change this
two points before installation.

So I would assume nearly all VMs created with our virt-manager are affected.

If qxl and usb redirection are not required, only recommend, we should not use
them by default...

And yes, quite some update paths install updates with "--no-recommends",
including some SLES update paths (Service-Packs, e.g.).
So we have to assume that the two packages are not only not registered, but
really not installed for many customers.