14 DAY TRIAL // Canonical announced today the availability of a new kernel update for the original Ubuntu 16.04 LTS (Xenial Xerus) operating system using the long-term supported Linux 4.4 kernel.
The update is a major one patching a total of 13 security flaws, including race conditions in Linux kernel's ALSA subsystem, the packet fanout implementation, and the key management subsystem, as well as use-after-free vulnerabilities in both the USB serial console driver and the ALSA subsystem.
Various other issues were also patched for Linux kernel's key management subsystem, the Ultra Wide Band driver, the ALSA subsystem, the USB unattached storage driver, and the USB subsystem, which received the most attention in this update as several security flaws were recently disclosed.
Most of these USB flaws could allow a physically proximate attacker to crash the system by causing a denial of service (DoS attack), but the rest of the issues patched in this new kernel update only allowed local attackers to cause a denial of service (system crash) or possibly execute arbitrary code.
Users are urged to update their installations immediately
If you're using Ubuntu 16.04 LTS (Xenial Xerus) with the Linux 4.4 kernel, you are urged to update your installation immediately to the linux-image 4.4.0.101.106 kernel that's now available in the software repositories for various of the supported hardware architectures. To update, follow the instructions at https://wiki.ubuntu.com/Security/Upgrades.
Canonical also released today a small kernel update for Ubuntu 17.04 (Zesty Zapus), which addresses an issue in Linux kernel's KVM subsystem that could allow a local attacker in the guest VM to crash the host operating system by causing a denial of service or possibly execute arbitrary code.
Ubuntu 17.04 users should update now to the linux-image 4.10.0.40.40 kernel or the linux-image-raspi2 4.10.0.1021.22 kernel for Ubuntu 17.04 for Raspberry Pi 2. An HWE (Hardware Enablement) kernel is also available for Ubuntu 16.04.3 LTS users using the Linux 4.10 kernel from Ubuntu 17.04, namely linux-image-hwe-16.04 4.10.0.40.42.
In addition, those using the Ubuntu 14.04.5 LTS (Trusty Tahr) operating system with the Linux 4.4 HWE kernel from Ubuntu 16.04 LTS also are required to update their installations to the linux-image-lts-xenial 4.4.0.101.84 kernel as it includes the same 13 security patches mentioned in the security advisories published today.