An Ubuntu Linux kernel security update fixes 12 security vulnerabilities affecting the Linux 5.4 LTS kernel in Ubuntu 20.04 LTS and Ubuntu 18.04 LTS systems, as well as the Linux 5.11 kernel in Ubuntu 21.04 systems on all supported architectures and platforms.

For all supported Ubuntu releases, the new Linux kernel security updates fix CVE-2021-33624, a security flaw discovered by Ofek Kirzner, Adam Morrison, Benedict Schlueter, and Piotr Krysiuk, which could leading to a side-channel attack, allowing an attacker to expose sensitive information, as well as CVE-2021-3679, a security issue discovered in the tracing subsystem that could allow a privileged attacker to cause a denial of service.