A Linux kernel security update has been released for Ubuntu Linux 18.04 LTS.

USN-4484-1: Linux kernel vulnerability

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Ubuntu Security Notice USN-4484-1
September 02, 2020

linux-hwe, linux-aws-5.3, linux-gke-5.3, linux-raspi2-5.3 vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS

Summary:

The system could be made to crash or run programs as an administrator.

Software Description:
- linux-aws-5.3: Linux kernel for Amazon Web Services (AWS) systems
- linux-gke-5.3: Linux kernel for Google Container Engine (GKE) systems
- linux-hwe: Linux hardware enablement (HWE) kernel
- linux-raspi2-5.3: Linux kernel for Raspberry Pi (V8) systems

Details:

It was discovered that the cgroup v2 subsystem in the Linux kernel did not
properly perform reference counting in some situations, leading to a NULL
pointer dereference. A local attacker could use this to cause a denial of
service or possibly gain administrative privileges. (CVE-2020-14356)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 18.04 LTS:
linux-image-5.3.0-1032-raspi2 5.3.0-1032.34
linux-image-5.3.0-1034-aws 5.3.0-1034.36
linux-image-5.3.0-1034-gke 5.3.0-1034.36
linux-image-5.3.0-66-generic 5.3.0-66.60
linux-image-5.3.0-66-lowlatency 5.3.0-66.60
linux-image-aws 5.3.0.1034.33
linux-image-gke-5.3 5.3.0.1034.19
linux-image-gkeop-5.3 5.3.0.66.123
linux-image-raspi2-hwe-18.04 5.3.0.1032.22

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References:
  https://usn.ubuntu.com/4484-1
CVE-2020-14356

Package Information:
  https://launchpad.net/ubuntu/+source/linux-aws-5.3/5.3.0-1034.36
  https://launchpad.net/ubuntu/+source/linux-gke-5.3/5.3.0-1034.36
  https://launchpad.net/ubuntu/+source/linux-hwe/5.3.0-66.60
  https://launchpad.net/ubuntu/+source/linux-raspi2-5.3/5.3.0-1032.34