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Ubuntu 20.04 LTS: USN-5120-1 Critical Denial Of Service Threats

ubuntu
Calendar Grey October 21, 2021
Dist Ubuntu Esm H88
Ubuntu Security Announcement USN-5121-1 addresses various kernel vulnerabilities necessitating updates to ensure sound security practices.
Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux-azure-5.8: Linux kernel for Microsoft Azure cloud systems

Details:

It was discovered that the f2fs file system in the Linux kernel did not

properly validate metadata in some situations. An attacker could use this

to construct a malicious f2fs image that, when mounted and operated on,

could cause a denial of service (system crash) or possibly execute

arbitrary code. (CVE-2019-19449)

It was discovered that the Linux kernel did not properly enforce certain

types of entries in the Secure Boot Forbidden Signature Database (aka dbx)

protection mechanism. An attacker could use this to bypass UEFI Secure Boot

restrictions. (CVE-2020-26541)

It was discovered that the KVM hypervisor implementation for AMD processorsin the Linux kernel did not ensure enough processing time was given to

perform cleanups of large SEV VMs. A local attacker could use this to cause

a denial of service (soft lockup). (CVE-202...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu kernel secure boot linux-azure

Update Instructions

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

Ubuntu 20.04 LTS:
  linux-image-5.8.0-1043-azure    5.8.0-1043.46~20.04.1
  linux-image-azure               5.8.0.1043.46~20.04.15

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-5120-1

CVE-2019-19449, CVE-2020-26541, CVE-2020-36311, CVE-2021-22543,

CVE-2021-3612, CVE-2021-3759, CVE-2021-38199, CVE-2021-38207,

CVE-2021-40490

Severity
critical
Lowest
Low
Medium
High
Critical

October 21, 2021

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu kernel secure boot linux-azure

Package Information

https://launchpad.net/ubuntu/+source/linux-azure-5.8/5.8.0-1043.46~20.04.1

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