The kernel security update addressed both the L1 Terminal Fault vulnerabilities, as well as two other security flaws (CVE-2018-5390 and CVE-2018-5391) discovered by Juha-Matti Tilli in Linux kernel’s TCP and IP implementations, which could allow remote attackers to cause a denial of service. Unfortunately, on Ubuntu 14.04 LTS (Trusty Tahr) systems, users reported that the mitigations also introduced a regression in the Linux kernel packages, which could cause kernel panics for some users that booted the OS in certain desktop environments.