Oracle Linux: CVE-2017-12188: ELSA-2018-0395: kernel security and bug fix update (IMPORTANT)

arch/x86/kvm/mmu.c in the Linux kernel through 4.13.5, when nested virtualisation is used, does not properly traverse guest pagetable entries to resolve a guest virtual address, which allows L1 guest OS users to execute arbitrary code on the host OS or cause a denial of service (incorrect index during page walking, and host OS crash), aka an "MMU potential stack buffer overrun."
The Linux kernel built with the KVM visualization support (CONFIG_KVM), with nested visualization(nVMX) feature enabled (nested=1), was vulnerable to a stack buffer overflow issue. The vulnerability could occur while traversing guest page table entries to resolve guest virtual address(gva). An L1 guest could use this flaw to crash the host kernel resulting in denial of service (DoS) or potentially execute arbitrary code on the host to gain privileges on the system.