=========================================================================Ubuntu Security Notice USN-3690-2
July 05, 2018

amd64-microcode regression
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 14.04 LTS

Summary:

The system could be made to expose sensitive information.

Software Description:
- amd64-microcode: Processor microcode firmware for AMD CPUs

Details:

USN-3690-1 provided updated microcode for AMD processors to address
CVE-2017-5715 (aka Spectre). Unfortunately, the update caused some
systems to fail to boot. This update reverts the update for Ubuntu
14.04 LTS.

We apologize for the inconvenience.

Original advisory details:

 Jann Horn discovered that microprocessors utilizing speculative execution
 and branch prediction may allow unauthorized memory reads via sidechannel
 attacks. This flaw is known as Spectre. A local attacker could use this to
 expose sensitive information, including kernel memory.

 This update provides the microcode updates for AMD 17H family
 processors required for the corresponding Linux kernel updates.

Update instructions:

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

Ubuntu 14.04 LTS:
  amd64-microcode                 3.20180524.1~ubuntu0.14.04.2+really20130710.1

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

References:
  https://ubuntu.com/security/notices/USN-3690-2
  https://ubuntu.com/security/notices/USN-3690-1
  https://bugs.launchpad.net/ubuntu/+source/amd64-microcode/+bug/1779092

Package Information:
  https://launchpad.net/ubuntu/+source/amd64-microcode/3.20180524.1~ubuntu0.14.04.2+really20130710.1