May be related to: https://github.com/kanaka/noVNC/issues/21

I've seen this problem too and it seems to be dependant on the version of libvirtd that was running at the time theforeman provisioned the VM.

On a SL6.3 hypervisor host, running these packages, I believe the problem is now gone for new VMs.

libvirt-python-0.9.10-21.el6_3.5.x86_64
libvirt-client-0.9.10-21.el6_3.5.x86_64
libvirt-0.9.10-21.el6_3.5.x86_64

What versions are you running?

I'm running Fedora 17 hypervisors :
rpm -qa | grep libvirt
libvirt-client-0.9.11.4-3.fc17.x86_64
libvirt-0.9.11.4-3.fc17.x86_64
libvirt-daemon-0.9.11.4-3.fc17.x86_64

The problem seems to have come back for me on all of my libvirt boxes and I'm still running:

libvirt-0.9.10-21.el6_3.5.x86_64
libvirt-python-0.9.10-21.el6_3.5.x86_64
libvirt-client-0.9.10-21.el6_3.5.x86_64

Forcibly setting the keymap to en_us, clearing the password, and destroying then starting the VM fixes not being able to access the console at all. However, this completely breaks the foreman novnc console with the error:

Failed to set console: Call to virDomainUpdateDeviceFlags failed: internal error cannot change keymap setting on vnc graphics