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Category:   Application (Generic)  >   Red Hat Enterprise Virtualization Vendors:   Red Hat
(Red Hat Issues Fix for Red Hat Enterprise Virtualization) Intel/AMD/ARM CPU Cache Race Conditions Let Local Users Read Arbitrary Register and Memory Contents
SecurityTracker Alert ID:  1040965
SecurityTracker URL:
CVE Reference:   CVE-2018-3639   (Links to External Site)
Date:  May 23 2018
Impact:   Disclosure of system information
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   Two vulnerabilities were reported in Intel, AMD, and ARM CPUs. A local user can obtain potentially sensitive information from system memory. Red Hat Enterprise Virtualization is affected.

A local user can exploit race conditions in CPU cache processing to obtain potentially sensitive information on the target system. This can be exploited to read arbitrary system register and memory contents on the target system.

A local user can conduct a side-channel attack to exploit a flaw in the speculative loading of system registers to read privileged system registers [CVE-2018-3640].

The CVE-2018-3640 vulnerability is referred to as "Spectre variant 3A".

A local user can conduct a side-channel attack to exploit a flaw in the speculative execution of Load and Store instructions to read privileged memory [CVE-2018-3639].

The CVE-2018-3639 vulnerability is referred to as "Spectre variant 4".

The original advisory is available at:

Zdenek Sojka, Rudolf Marek, and Alex Zuepke from SYSGO AG, Jann Horn (Google Project Zero), and Ken Johnson (Microsoft Security Response Center) reported these vulnerabilities.

Impact:   A local user can view system register or memory contents on the target CPU device.
Solution:   Red Hat has issued a fix for CVE-2018-3639 for Red Hat Enterprise Virtualization.

The Red Hat advisory is available at:

Vendor URL: (Links to External Site)
Cause:   Access control error, State error
Underlying OS:  Linux (Red Hat Enterprise)
Underlying OS Comments:  6, 7

Message History:   This archive entry is a follow-up to the message listed below.
May 22 2018 Intel/AMD/ARM CPU Cache Race Conditions Let Local Users Read Arbitrary Register and Memory Contents

 Source Message Contents

Subject:  [RHSA-2018:1711-01] Important: rhev-hypervisor7 security update

Hash: SHA256

                   Red Hat Security Advisory

Synopsis:          Important: rhev-hypervisor7 security update
Advisory ID:       RHSA-2018:1711-01
Product:           Red Hat Virtualization
Advisory URL:
Issue date:        2018-05-23
CVE Names:         CVE-2018-3639 

1. Summary:

An update for rhev-hypervisor7 is now available for RHEV 3.X Hypervisor and
Agents Extended Lifecycle Support for Red Hat Enterprise Linux 6 and RHEV
3.X Hypervisor and Agents Extended Lifecycle Support for Red Hat Enterprise
Linux 7.

Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.

2. Relevant releases/architectures:

RHEL 7-based RHEV-H ELS - noarch
RHEV Hypervisor for RHEL-6 ELS - noarch

3. Description:

The rhev-hypervisor7 package provides a Red Hat Enterprise Virtualization
Hypervisor ISO disk image. The Red Hat Enterprise Virtualization Hypervisor
is a dedicated Kernel-based Virtual Machine (KVM) hypervisor. It includes
everything necessary to run and manage virtual machines: A subset of the
Red Hat Enterprise Linux operating environment and the Red Hat Enterprise
Virtualization Agent.

Security Fix(es):

* An industry-wide issue was found in the way many modern microprocessor
designs have implemented speculative execution of Load & Store instructions
(a commonly used performance optimization). It relies on the presence of a
precisely-defined instruction sequence in the privileged code as well as
the fact that memory read from address to which a recent memory write has
occurred may see an older value and subsequently cause an update into the
microprocessor's data cache even for speculatively executed instructions
that never actually commit (retire). As a result, an unprivileged attacker
could use this flaw to read privileged memory by conducting targeted cache
side-channel attacks. (CVE-2018-3639)

Note: This is the rhev-hypervisor7 side of the CVE-2018-3639 mitigation.

Red Hat would like to thank Ken Johnson (Microsoft Security Response
Center) and Jann Horn (Google Project Zero) for reporting this issue.

4. Solution:

For details on how to apply this update, which includes the changes
described in this advisory, refer to:

5. Bugs fixed (

1566890 - CVE-2018-3639 hw: cpu: speculative store bypass

6. Package List:

RHEV Hypervisor for RHEL-6 ELS:



RHEL 7-based RHEV-H ELS:



These packages are GPG signed by Red Hat for security.  Our key and
details on how to verify the signature are available from

7. References:

8. Contact:

The Red Hat security contact is <>. More contact
details at

Copyright 2018 Red Hat, Inc.
Version: GnuPG v1


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