Ubuntu 21.04 & 20.04 LTS Security Advisory: Critical Kernel Threats

ubuntu

August 17, 2021

Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux: Linux kernel

- linux-aws: Linux kernel for Amazon Web Services (AWS) systems

- linux-azure: Linux kernel for Microsoft Azure Cloud systems

- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems

- linux-oracle: Linux kernel for Oracle Cloud systems

- linux-raspi: Linux kernel for Raspberry Pi (V8) systems

- linux-hwe-5.11: Linux hardware enablement (HWE) kernel

Details:

It was discovered that the bluetooth subsystem in the Linux kernel did not

properly perform access control. An authenticated attacker could possibly

use this to expose sensitive information. (CVE-2020-26558, CVE-2021-0129)

Michael Brown discovered that the Xen netback driver in the Linux kernel

did not properly handle malformed packets from a network PV frontend,

leading to a use-after-free vulnerability. An attacker in a guest VM could

use this to cause a denial of service or possibly execute arbitrary code.

(CVE-20...

Read the Full Advisory

Topics Covered

security advisory denial of service network security buffer overflow access control ubuntu linux kernel

Update Instructions

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

Ubuntu 21.04:
  linux-image-5.11.0-1013-azure   5.11.0-1013.14
  linux-image-5.11.0-1016-aws     5.11.0-1016.17
  linux-image-5.11.0-1016-oracle  5.11.0-1016.17
  linux-image-5.11.0-1016-raspi   5.11.0-1016.17
  linux-image-5.11.0-1016-raspi-nolpae  5.11.0-1016.17
  linux-image-5.11.0-1017-gcp     5.11.0-1017.19
  linux-image-5.11.0-31-generic   5.11.0-31.33
  linux-image-5.11.0-31-generic-64k  5.11.0-31.33
  linux-image-5.11.0-31-generic-lpae  5.11.0-31.33
  linux-image-5.11.0-31-lowlatency  5.11.0-31.33
  linux-image-aws                 5.11.0.1016.17
  linux-image-azure               5.11.0.1013.14
  linux-image-gcp                 5.11.0.1017.17
  linux-image-generic             5.11.0.31.33
  linux-image-generic-64k         5.11.0.31.33
  linux-image-generic-lpae        5.11.0.31.33
  linux-image-gke                 5.11.0.1017.17
  linux-image-lowlatency          5.11.0.31.33
  linux-image-oem-20.04           5.11.0.31.33
  linux-image-oracle              5.11.0.1016.17
  linux-image-raspi               5.11.0.1016.14
  linux-image-raspi-nolpae        5.11.0.1016.14
  linux-image-virtual             5.11.0.31.33

Ubuntu 20.04 LTS:
  linux-image-5.11.0-27-generic   5.11.0-27.29~20.04.1
  linux-image-5.11.0-27-generic-64k  5.11.0-27.29~20.04.1
  linux-image-5.11.0-27-generic-lpae  5.11.0-27.29~20.04.1
  linux-image-5.11.0-27-lowlatency  5.11.0-27.29~20.04.1
  linux-image-generic-64k-hwe-20.04  5.11.0.27.29~20.04.11
  linux-image-generic-hwe-20.04   5.11.0.27.29~20.04.11
  linux-image-generic-lpae-hwe-20.04  5.11.0.27.29~20.04.11
  linux-image-lowlatency-hwe-20.04  5.11.0.27.29~20.04.11
  linux-image-virtual-hwe-20.04   5.11.0.27.29~20.04.11

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.