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

USN-5002-1: Linux kernel (HWE) vulnerability

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Ubuntu Security Notice USN-5002-1
June 23, 2021

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

- Ubuntu 18.04 LTS

Summary:

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

Software Description:
- 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:

Norbert Slusarek discovered a race condition in the CAN BCM networking
protocol of the Linux kernel leading to multiple use-after-free
vulnerabilities. A local attacker could use this issue to execute arbitrary
code.

Update instructions:

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

Ubuntu 18.04 LTS:
linux-image-5.3.0-1041-raspi2 5.3.0-1041.43
linux-image-5.3.0-1044-gke 5.3.0-1044.47
linux-image-5.3.0-75-generic 5.3.0-75.71
linux-image-5.3.0-75-lowlatency 5.3.0-75.71
linux-image-gke-5.3 5.3.0.1044.27
linux-image-gkeop-5.3 5.3.0.75.132
linux-image-raspi2-hwe-18.04 5.3.0.1041.30

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://ubuntu.com/security/notices/USN-5002-1
CVE-2021-3609

Package Information:
  https://launchpad.net/ubuntu/+source/linux-gke-5.3/5.3.0-1044.47
  https://launchpad.net/ubuntu/+source/linux-hwe/5.3.0-75.71
  https://launchpad.net/ubuntu/+source/linux-raspi2-5.3/5.3.0-1041.43