Xen x86 CR0.TS and CR0.EM Honoring Cross-task Register State Information Disclosure (XSA-190)

medium Nessus Plugin ID 94162

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Synopsis

The remote Xen hypervisor installation is missing a security update.

Description

According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by an information disclosure vulnerability in x86_emulate.c due to a failure to properly honor CR0.TS and CR0.EM. A local attacker within an x86 HVM guest operating system can exploit this, by modifying an instruction while the hypervisor is preparing to emulate it, to read or manipulate FPU, MMX, or XMM register state information for other tasks running in the guest.

Note that Nessus has checked the changeset versions based on the xen.git change log. Nessus did not check guest hardware configurations or if patches were applied manually to the source code before a recompile and reinstall.

Solution

Apply the appropriate patch according to the vendor advisory.

Plugin Details

Severity: Medium

ID: 94162

File Name: xen_server_XSA-190.nasl

Version: 1.8

Type: local

Family: Misc.

Published: 10/20/2016

Updated: 7/10/2020

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.2

CVSS v2

Risk Factor: Low

Base Score: 3.3

Temporal Score: 2.4

Vector: CVSS2#AV:L/AC:M/Au:N/C:P/I:P/A:N

CVSS v3

Risk Factor: Medium

Base Score: 6.3

Temporal Score: 5.5

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:xen:xen

Required KB Items: installed_sw/Xen Hypervisor, Settings/ParanoidReport

Exploit Ease: No known exploits are available

Patch Publication Date: 10/4/2016

Vulnerability Publication Date: 10/4/2016

Reference Information

CVE: CVE-2016-7777

BID: 93344

IAVB: 2016-B-0149-S

Detections

Analytics