We’ve prepared new kernels for the legacy VM platform to prevent the futex privilege escalation bug CVE-2014-3153.
If your current kernel is set to one of Stable-i386.kvm, AppArmor-i386.kvm, Experimental-i386.kvm, Linux3.2-i386.kvm or Linux3.4-i386.kvm then restarting your VM is sufficient to get protection. Otherwise you should change your kernel to one of the above. They currently map to these kernel versions:
Stable-i386.kvm -> linux-220.127.116.11-kvm-i386-20140610
AppArmor-i386.kvm -> linux-18.104.22.168-kvm-i386-20140610
Experimental-i386.kvm -> linux-3.2.60-kvm-i386-20140609
Linux3.2-i386.kvm -> linux-3.2.60-kvm-i386-20140609
Linux3.4-i386.kvm -> linux-3.4.92-kvm-i386-20140609
We are also starting a programme of VM migrations which will also involve a restart (you will have been contacted by email if this affects you soon), so you may wish to wait for that to avoid having two VM restarts.