XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x on Intel/Cyrix vmx_vmexit_handler null pointer dereference

CVSS Meta Temp Score
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5.9$0-$5k0.00

A vulnerability was found in XenSource Xen 4.3.x/4.4.x/4.5.x/4.6.x on Intel/Cyrix (Virtualization Software). It has been declared as critical. Affected by this vulnerability is the function vmx_vmexit_handler. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

VMX in Xen 4.6.x and earlier, when using an Intel or Cyrix CPU, allows local HVM guest users to cause a denial of service (guest crash) via vectors related to a non-canonical RIP.

The weakness was published 02/18/2016 by Ling Liu with Qihoo 360 as XSA-170 as confirmed security advisory (Website). The advisory is shared at xenbits.xen.org. This vulnerability is known as CVE-2016-2271 since 02/08/2016. An attack has to be approached locally. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 89629 (Fedora 23 : xen-4.5.2-8.fc23 (2016-e48f4bd14f)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Fedora Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 370023 (Citrix XenServer Security Update (CTX209443)).

Applying the patch xsa170-4.3.patch/xsa170-4.5.patch/xsa170.patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (89629). Similar entries are available at 76871, 81024, 81555 and 81556.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB CVSS-B Score: 🔍
VulDB CVSS-BT Score: 🔍
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CVSSv3info

VulDB Meta Base Score: 6.2
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.8
VulDB Temp Score: 6.5
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
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Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
ATT&CK: Unknown

Local: Yes
Remote: No

Availability: 🔍
Status: Not defined

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EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 89629
Nessus Name: Fedora 23 : xen-4.5.2-8.fc23 (2016-e48f4bd14f)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 850584
OpenVAS Name: SuSE Update for xen SUSE-SU-2016:1318-1 (xen)
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
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Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Patch: xsa170-4.3.patch/xsa170-4.5.patch/xsa170.patch

Timelineinfo

02/08/2016 🔍
02/16/2016 +8 days 🔍
02/18/2016 +1 days 🔍
02/18/2016 +0 days 🔍
02/18/2016 +0 days 🔍
02/18/2016 +0 days 🔍
02/19/2016 +0 days 🔍
02/19/2016 +0 days 🔍
02/20/2016 +1 days 🔍
03/03/2016 +12 days 🔍
08/23/2018 +902 days 🔍

Sourcesinfo

Vendor: citrix.com

Advisory: XSA-170
Researcher: Ling Liu
Organization: Qihoo 360
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2016-2271 (🔍)
OVAL: 🔍

SecurityTracker: 1035043
Vulnerability Center: 56681 - Xen 4.6.x and Earlier Local DoS in VMX, Low
SecurityFocus: 83292 - Xen CVE-2016-2271 Denial of Service Vulnerability

See also: 🔍

Entryinfo

Created: 02/19/2016 10:15
Updated: 08/23/2018 08:17
Changes: 02/19/2016 10:15 (75), 08/23/2018 08:17 (19)
Complete: 🔍

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