CVE-2018-1087 (https://nvd.nist.gov/vuln/detail/CVE-2018-1087): A flaw was found in the way the Linux kernel's KVM hypervisor handled exceptions delivered after a stack switch operation via Mov SS or Pop SS instructions. During the stack switch operation, the processor did not deliver interrupts and exceptions, rather they are delivered once the first instruction after the stack switch is executed. An unprivileged KVM guest user could use this flaw to crash the guest or, potentially, escalate their privileges in the guest.
Upstream fix: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=32d43cd391bacb5f0814c2624399a5dad3501d09
Fixed in >=sys-kernel/gentoo-sources-4.4.125, 4.4.128 is currently being stabilized in bug 653958 >=sys-kernel/gentoo-sources-4.9.91, 4.9.95 is currently being stabilized in bug 653956
Fix in 4.9.91, 4.14.31, 4.16