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Ubuntu 20.04: USN-5082-1 Critical Memory Access Threat from Linux Kernel

ubuntu
Calendar Grey September 16, 2021
Dist Ubuntu Esm H88
The Ubuntu 5082-1 advisory highlights critical kernel vulnerabilities in the OS that risk unauthorized access and privilege escalation, necessitating immediate action
Several security issues were fixed in the Linux kernel.

Summary

Several security issues were fixed in the Linux kernel.

Software Description:

- linux-oem-5.13: Linux kernel for OEM systems

Details:

Maxim Levitsky and Paolo Bonzini discovered that the KVM hypervisor

implementation for AMD processors in the Linux kernel allowed a guest VM to

disable restrictions on VMLOAD/VMSAVE in a nested guest. An attacker in a

guest VM could use this to read or write portions of the host's physical

memory. (CVE-2021-3656)

Maxim Levitsky discovered that the KVM hypervisor implementation for AMD

processors in the Linux kernel did not properly prevent a guest VM from

enabling AVIC in nested guest VMs. An attacker in a guest VM could use this

to write to portions of the host's physical memory. (CVE-2021-3653)

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. (CVE-2021-3609)

Topics%20covered

Topics Covered

security advisory critical threat memory access ubuntu linux kernel KVM OEM systems

Update Instructions

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

Ubuntu 20.04 LTS:
  linux-image-5.13.0-1012-oem     5.13.0-1012.16
  linux-image-oem-20.04c          5.13.0.1012.16

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-5082-1

CVE-2021-3609, CVE-2021-3653, CVE-2021-3656

Severity
critical
Lowest
Low
Medium
High
Critical

September 16, 2021

Topics%20covered

Topics Covered

security advisory critical threat memory access ubuntu linux kernel KVM OEM systems

Package Information

https://launchpad.net/ubuntu/+source/linux-oem-5.13/5.13.0-1012.16

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