CVE-2016-4020
First published: Wed Mar 02 2016(Updated: )
The patch_instruction function in hw/i386/kvmvapic.c in QEMU does not initialize the imm32 variable, which allows local guest OS administrators to obtain sensitive information from host stack memory by accessing the Task Priority Register (TPR).
Credit: secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| QEMU KVM | <=2.6.2 | |
| Ubuntu | =12.04 | |
| Ubuntu | =14.04 | |
| Ubuntu | =15.10 | |
| Ubuntu | =16.04 | |
| Debian | =8.0 | |
| redhat openstack | =6.0 | |
| redhat openstack | =7.0 | |
| redhat openstack | =8 | |
| redhat openstack | =9 | |
| redhat openstack | =10 | |
| redhat openstack | =11 | |
| redhat enterprise Linux desktop | =7.0 | |
| redhat enterprise Linux eus | =7.4 | |
| redhat enterprise Linux eus | =7.5 | |
| redhat enterprise Linux eus | =7.6 | |
| redhat enterprise Linux eus | =7.7 | |
| redhat enterprise Linux server | =7.0 | |
| redhat enterprise Linux server aus | =7.4 | |
| redhat enterprise Linux server aus | =7.6 | |
| redhat enterprise Linux server aus | =7.7 | |
| redhat enterprise Linux server tus | =7.6 | |
| redhat enterprise Linux server tus | =7.7 | |
| redhat enterprise Linux workstation | =7.0 | |
| Red Hat Enterprise Virtualization | =4.0 | |
| Red Hat Enterprise Linux | =7.0 |
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Reference Links
- http://git.qemu.org/?p=qemu.git%3Ba=commit%3Bh=691a02e2ce0c413236a78dee6f2651c937b09fb0
- http://www.securityfocus.com/bid/86067
- http://www.ubuntu.com/usn/USN-2974-1
- https://access.redhat.com/errata/RHSA-2017:1856
- https://access.redhat.com/errata/RHSA-2017:2392
- https://access.redhat.com/errata/RHSA-2017:2408
- https://bugzilla.redhat.com/show_bug.cgi?id=1313686
- https://lists.debian.org/debian-lts-announce/2018/11/msg00038.html
- https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01106.html
- https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg01118.html
- https://security.gentoo.org/glsa/201609-01
- http://www.openwall.com/lists/oss-security/2016/04/14/3
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1326904
- https://access.redhat.com/support/policy/updates/errata/
Frequently Asked Questions
What is the severity of CVE-2016-4020?
CVE-2016-4020 has a moderate severity rating, as it allows local guest OS administrators to access sensitive information from the host's memory.
How do I fix CVE-2016-4020?
To mitigate CVE-2016-4020, update QEMU to the latest version or apply the patched versions indicated by your distribution.
Is CVE-2016-4020 exploitable remotely?
No, CVE-2016-4020 is not remotely exploitable as the attack requires local access to the guest OS.
Which software versions are affected by CVE-2016-4020?
CVE-2016-4020 affects various versions of QEMU up to and including 2.6.2 and specific versions of Ubuntu and Red Hat OpenStack.
What types of systems are vulnerable to CVE-2016-4020?
Systems running vulnerable versions of QEMU, Ubuntu 12.04, 14.04, 15.10, 16.04, and various Red Hat OpenStack versions are susceptible to CVE-2016-4020.
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