Several security issues were fixed in the kernel.
A flaw was discovered in the Linux kernel’s KVM (kernel virtual machine). An administrative user in the guest OS could leverage this flaw to cause a denial of service in the host OS. (CVE-2012-2121)
3 December 2013
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in the kernel.
A flaw was discovered in the Linux kernel’s KVM (kernel virtual machine). An administrative user in the guest OS could leverage this flaw to cause a denial of service in the host OS. (CVE-2012-2121)
Multiple integer overflow flaws were discovered in the Alchemy LCD frame- buffer drivers in the Linux kernel. An unprivileged local user could exploit this flaw to gain administrative privileges. (CVE-2013-4511)
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to reboot your computer to make all the necessary changes.
ATTENTION: Due to an unavoidable ABI change the kernel updates have been given a new version number, which requires you to recompile and reinstall all third party kernel modules you might have installed. If you use linux-restricted-modules, you have to update that package as well to get modules which work with the new kernel version. Unless you manually uninstalled the standard kernel metapackages (e.g. linux-generic, linux-server, linux-powerpc), a standard system upgrade will automatically perform this as well.