The respective security notice contained information about four kernel vulnerabilities that affected the Linux 4.4 LTS kernel packages of Ubuntu 16.04 LTS (Xenial Xerus) on all supported architectures, including 64-bit and 32-bit, Raspberry Pi 2, Snapdragon processors, as well as Amazon Web Services (AWS) and Google Container Engine (GKE) systems. However, the security patch introduced a regression that apparently prevented the conntrack component, Netfilter’s connection tracking userspace tool, to work correctly under certain conditions. Therefore, Canonical is today releasing updated Linux 4.4 kernel packages for Ubuntu 16.04 LTS with a fix for said regression, urging users to update their systems immediately.