Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2020-25602

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
23/09/2020
Last modified:
07/11/2023

Description

An issue was discovered in Xen through 4.14.x. An x86 PV guest can trigger a host OS crash when handling guest access to MSR_MISC_ENABLE. When a guest accesses certain Model Specific Registers, Xen first reads the value from hardware to use as the basis for auditing the guest access. For the MISC_ENABLE MSR, which is an Intel specific MSR, this MSR read is performed without error handling for a #GP fault, which is the consequence of trying to read this MSR on non-Intel hardware. A buggy or malicious PV guest administrator can crash Xen, resulting in a host Denial of Service. Only x86 systems are vulnerable. ARM systems are not vulnerable. Only Xen versions 4.11 and onwards are vulnerable. 4.10 and earlier are not vulnerable. Only x86 systems that do not implement the MISC_ENABLE MSR (0x1a0) are vulnerable. AMD and Hygon systems do not implement this MSR and are vulnerable. Intel systems do implement this MSR and are not vulnerable. Other manufacturers have not been checked. Only x86 PV guests can exploit the vulnerability. x86 HVM/PVH guests cannot exploit the vulnerability.

Impact

Vector 3.x
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 6.00 MEDIUM
Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H

Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): High
User Interaction (UI): None
Scope (S): Changed
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x
6.00
Severity 3.x
MEDIUM
Vector 2.0
AV:L/AC:L/Au:S/C:N/I:N/A:C CVSS v2.0 Severity and Metrics:

Base Score: 4.60 MEDIUM
Vector: AV:L/AC:L/Au:S/C:N/I:N/A:C

Attack Vector (AV): Local
Attack Complexity (AC): Low
Authentication (Au): Single
Confidentiality (C): None
Integrity (I): None
Availability (A): Complete

Base Score 2.0
4.60
Severity 2.0
MEDIUM

Vulnerable products and versions

CPE From Up to
cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:* 4.11.0 (including) 4.14.0 (including)
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools