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Xen x86 PV guest kernels DoS (XSA-339)

medium Nessus Plugin ID 141501

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Synopsis

The remote Xen hypervisor installation is missing a security update.

Description

A denial of service (DoS) vulnerability exists in Xen servers when using x86 PV guest kernels due to a mishandling of SYSENTER state sanitization activities. An authenticated, local attacker can exploit this issue, via the SYSENTER instruction in 64bit mode, to cause a VM Denial of Service.

Note that only x86 PV guests can exploit the vulnerability.

Solution

Apply the appropriate patch according to the vendor advisory or by running only x86 PVH / HVM guests avoids the vulnerability.

See Also

https://xenbits.xen.org/xsa/advisory-339.htmll

Plugin Details

Severity: Medium

ID: 141501

File Name: xen_server_XSA-339.nasl

Version: 1.4

Type: local

Family: Misc.

Published: 10/19/2020

Updated: 11/13/2020

Configuration: Enable paranoid mode

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Low

Base Score: 2.1

Temporal Score: 1.6

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

CVSS Score Source: CVE-2020-25596

CVSS v3

Risk Factor: Medium

Base Score: 5.5

Temporal Score: 4.8

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

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: 9/22/2020

Vulnerability Publication Date: 9/22/2020

Reference Information

CVE: CVE-2020-25596

IAVB: 2020-B-0056-S