(Red Hat Issues Fix for KVM) QEMU Floppy Disk Controller Emulation Flaw Lets Local Users Gain Elevated Privileges
SecurityTracker Alert ID: 1032312|
SecurityTracker URL: http://securitytracker.com/id/1032312
(Links to External Site)
Date: May 13 2015
User access via local system|
Fix Available: Yes Vendor Confirmed: Yes |
A vulnerability was reported in QEMU. A local user on the guest system can obtain elevated privileges on the target host system. KVM is affected.|
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.
A local user on the guest system can obtain elevated privileges on the target host system.|
Red Hat has issued an advisory for KVM.|
The Red Hat advisory is available at:
Vendor URL: wiki.qemu.org/Main_Page (Links to External Site)
Access control error|
|Underlying OS: Linux (Red Hat Enterprise)|
|Underlying OS Comments: 5|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Subject: [RHSA-2015:1003-01] Important: kvm security update|
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Red Hat Security Advisory
Synopsis: Important: kvm security update
Advisory ID: RHSA-2015:1003-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2015-1003.html
Issue date: 2015-05-13
CVE Names: CVE-2015-3456
Updated kvm packages that fix one security issue are now available for Red
Hat Enterprise Linux 5.
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
2. Relevant releases/architectures:
RHEL Desktop Multi OS (v. 5 client) - x86_64
RHEL Virtualization (v. 5 server) - x86_64
KVM (Kernel-based Virtual Machine) is a full virtualization solution for
Linux on AMD64 and Intel 64 systems.
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
All kvm users are advised to upgrade to these updated packages, which
contain a backported patch to correct this issue. Note: The procedure in
the Solution section must be performed before this update will take effect.
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:
The following procedure must be performed before this update will take
1) Stop all KVM guest virtual machines.
2) Either reboot the hypervisor machine or, as the root user, remove (using
"modprobe -r [module]") and reload (using "modprobe [module]") all of the
following modules which are currently running (determined using "lsmod"):
kvm, ksm, kvm-intel or kvm-amd.
3) Restart the KVM guest virtual machines.
5. Bugs fixed (https://bugzilla.redhat.com/):
1218611 - CVE-2015-3456 qemu: fdc: out-of-bounds fifo buffer memory access
6. Package List:
RHEL Desktop Multi OS (v. 5 client):
RHEL Virtualization (v. 5 server):
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
The Red Hat security contact is <email@example.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2015 Red Hat, Inc.
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