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Category:   Application (Generic)  >   QEMU Vendors:
(Red Hat Issues Fix) QEMU Floppy Disk Controller Emulation Flaw Lets Local Users Gain Elevated Privileges
SecurityTracker Alert ID:  1032319
SecurityTracker URL:
CVE Reference:   CVE-2015-3456   (Links to External Site)
Date:  May 13 2015
Impact:   User access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 2.3.0 and prior versions
Description:   A vulnerability was reported in QEMU. A local user on the guest system can obtain elevated privileges on the target host system.

A local user on the guest system can supply specially crafted commands (e.g., FD_CMD_READ_ID, FD_CMD_DRIVE_SPECIFICATION_COMMAND) to trigger a memory corruption error and execute arbitrary code on the target host system with the privileges of the QEMU process on the host.

VMware, Microsoft Hyper-V, and Bochs hypervisors are not affected.

The original advisory is available at:

Jason Geffner, CrowdStrike Senior Security Researcher, reported this vulnerability.

Impact:   A local user on the guest system can obtain elevated privileges on the target host system.
Solution:   Red Hat has issued a fix.

The Red Hat advisories are available at:

Vendor URL: (Links to External Site)
Cause:   Access control 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 13 2015 QEMU Floppy Disk Controller Emulation Flaw Lets Local Users Gain Elevated Privileges

 Source Message Contents

Subject:  [RHSA-2015:1000-01] Important: qemu-kvm-rhev security update

Hash: SHA1

                   Red Hat Security Advisory

Synopsis:          Important: qemu-kvm-rhev security update
Advisory ID:       RHSA-2015:1000-01
Product:           Red Hat Enterprise Virtualization
Advisory URL:
Issue date:        2015-05-13
CVE Names:         CVE-2015-3456 

1. Summary:

Updated qemu-kvm-rhev packages that fix one security issue are now
available for Red Hat Enterprise Virtualization Hypervisor 7.

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

2. Relevant releases/architectures:

RHEV-H and VDSM for 7 Hosts - x86_64

3. Description:

KVM (Kernel-based Virtual Machine) is a full virtualization solution for
Linux on AMD64 and Intel 64 systems. The qemu-kvm-rhev package provides the
user-space component for running virtual machines using KVM.

An out-of-bounds memory access flaw was found in the way QEMU's virtual
Floppy Disk Controller (FDC) handled FIFO buffer access while processing
certain FDC commands. A privileged guest user could use this flaw to crash
the guest or, potentially, execute arbitrary code on the host with the
privileges of the host's QEMU process corresponding to the guest.

Red Hat would like to thank Jason Geffner of CrowdStrike for reporting
this issue.

All qemu-kvm-rhev users are advised to upgrade to these updated packages,
which contain a backported patch to correct this issue. After installing
this update, shut down all running virtual machines. Once all virtual
machines have shut down, start them again for this update to take effect.

4. Solution:

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, refer to:

5. Bugs fixed (

1218611 - CVE-2015-3456 qemu: fdc: out-of-bounds fifo buffer memory access

6. Package List:

RHEV-H and VDSM for 7 Hosts:



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 2015 Red Hat, Inc.
Version: GnuPG v1


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