#VU766 Information disclosure in Xen and Oracle VM Server for x86 - CVE-2016-7777

Vulnerability identifier: #VU766

Vulnerability risk: Low

CVSSv4.0: 1.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2016-7777

CWE-ID: CWE-284

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Xen
Server applications / Virtualization software
Oracle VM Server for x86
Server applications / Other server solutions

Vendor: Xen Project
Oracle

Description
The vulnerability allows a local unprivileged user to obtain potentially sensitive information on the guest system.
The weakness is caused by insufficient access control mechanisms. A local unprivileged user of a guest operating system can trigger the Xen instruction emulator by attempting to execute an invalid opcode and read or modify FPU, MMX, and XMM register state data of another process within the same guest system.
Successful exploitation of the vulnerability leads to register state information disclosure and corruption.

Mitigation
Update to version 5 or apply the following patches:

XSA-190 version 4.5.
http://xenbits.xen.org/xsa/xsa190-4.5.patch
XSA-190 version 4.6.
http://xenbits.xen.org/xsa/xsa190-4.6.patch

Vulnerable software versions

Xen: 4.4.0 - 4.7.0

Oracle VM Server for x86: 3.2 - 3.4

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External links
https://xenbits.xen.org/xsa/advisory-190.html
https://www.oracle.com/technetwork/topics/security/ovmbulletinoct2016-3090547.html

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.