(Red Hat Issues Fix for KVM) Xen Qemu VGA Module Bugs Let Local Users on the Guest Deny Service on the Guest or Gain Elevated Privileges on the Host System
SecurityTracker Alert ID: 1036906|
SecurityTracker URL: http://securitytracker.com/id/1036906
(Links to External Site)
Date: Sep 27 2016
Denial of service via network, User access via local system|
Fix Available: Yes Vendor Confirmed: Yes |
Two vulnerabilities were reported in Xen. A local user on the guest system can cause denial of service conditions on the guest system. A local user on the guest system can gain elevated privileges on the host system. KVM is affected.|
A privileged local user on the guest system can exploit a flaw in the Qemu VGA module to modify memory access modes and potentially execute arbitrary code with the privileges of the Qemu process [CVE-2016-3710].
A local user on the guest system can exploit a flaw in the Qemu VGA module to edit certain registers and trigger an out-of-bounds memory read error or integer overflow and cause denial of service conditions on the guest system [CVE-2016-3712].
Systems running on x86 with HVM guests with the qemu process running in dom0 are affected.
ARM systems are not affected.
Systems running only PV guests are not affected.
"Wei Xiao and Qinghao Tang of 360 Marvel Team" of 360.cn Inc. and Zuozhi Fzz of Alibaba Inc. reported these vulnerabilities.
A local user on the guest system can cause denial of service conditions on the guest system.|
A local user on the guest system can gain elevated privileges on the host system.
Red Hat has issued a fix for CVE-2016-3710 for KVM.|
The Red Hat advisory is available at:
Vendor URL: rhn.redhat.com/errata/RHSA-2016-1943.html (Links to External Site)
Access control error, Boundary 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-2016:1943-01] Important: kvm security update|
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Red Hat Security Advisory
Synopsis: Important: kvm security update
Advisory ID: RHSA-2016:1943-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2016-1943.html
Issue date: 2016-09-27
CVE Names: CVE-2016-3710 CVE-2016-5403
An update for kvm is now available for Red Hat Enterprise Linux 5.
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:
Red Hat Enterprise Linux Desktop Multi OS (v. 5 client) - x86_64
Red Hat Enterprise Linux Virtualization (v. 5 server) - x86_64
KVM (for Kernel-based Virtual Machine) is a full virtualization solution
for Linux on x86 hardware. Using KVM, one can run multiple virtual machines
running unmodified Linux or Windows images. Each virtual machine has
private virtualized hardware: a network card, disk, graphics adapter, etc.
* An out-of-bounds read/write access flaw was found in the way QEMU's VGA
emulation with VESA BIOS Extensions (VBE) support performed read/write
operations using I/O port methods. A privileged guest user could use this
flaw to execute arbitrary code on the host with the privileges of the
host's QEMU process. (CVE-2016-3710)
* Quick Emulator(QEMU) built with the virtio framework is vulnerable to an
unbounded memory allocation issue. It was found that a malicious guest user
could submit more requests than the virtqueue size permits. Processing a
request allocates a VirtQueueElement results in unbounded memory allocation
on the host controlled by the guest. (CVE-2016-5403)
Red Hat would like to thank Wei Xiao (360 Marvel Team) and Qinghao Tang
(360 Marvel Team) for reporting CVE-2016-3710 and hongzhenhao (Marvel Team)
for reporting CVE-2016-5403.
For details on how to apply this update, which includes the changes
described in this advisory, refer to:
Note: The procedure in the Solution section must be performed before this
update will take effect.
5. Bugs fixed (https://bugzilla.redhat.com/):
1331401 - CVE-2016-3710 qemu: incorrect banked access bounds checking in vga module
1358359 - CVE-2016-5403 Qemu: virtio: unbounded memory allocation on host via guest leading to DoS
6. Package List:
Red Hat Enterprise Linux Desktop Multi OS (v. 5 client):
Red Hat Enterprise Linux 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 <firstname.lastname@example.org>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2016 Red Hat, Inc.
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