CVE-2020-25596

Severity Score

5.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

An issue was discovered in Xen through 4.14.x. x86 PV guest kernels can experience denial of service via SYSENTER. The SYSENTER instruction leaves various state sanitization activities to software. One of Xen's sanitization paths injects a #GP fault, and incorrectly delivers it twice to the guest. This causes the guest kernel to observe a kernel-privilege #GP fault (typically fatal) rather than a user-privilege #GP fault (usually converted into SIGSEGV/etc.). Malicious or buggy userspace can crash the guest kernel, resulting in a VM Denial of Service. All versions of Xen from 3.2 onwards are vulnerable. Only x86 systems are vulnerable. ARM platforms are not vulnerable. Only x86 systems that support the SYSENTER instruction in 64bit mode are vulnerable. This is believed to be Intel, Centaur, and Shanghai CPUs. AMD and Hygon CPUs are not believed to be vulnerable. Only x86 PV guests can exploit the vulnerability. x86 PVH / HVM guests cannot exploit the vulnerability.

Se detectó un problema en Xen versiones hasta 4.14.x. Los kernels invitados de PV x86 pueden experimentar una denegación de servicio a través de SYSENTER. La instrucción de SYSENTER deja varias actividades de saneamiento del estado para el software. Una de las rutas de saneamiento de Xen inyecta un fallo #GP y la entrega incorrectamente dos veces al invitado. Esto causa que el kernel invitado observe un fallo de #GP de privilegios de kernel (generalmente fatal) en lugar de un fallo de #GP de privilegios de usuario (generalmente convertida a SIGSEGV/etc.). El espacio de usuario malicioso o con errores puede bloquear el kernel invitado, lo que resulta en una denegación de servicio de la VM. Todas las versiones de Xen desde 3.2 en adelante son vulnerables. Solo los sistemas x86 son vulnerables. Las plataformas ARM no son vulnerables. Solo los sistemas x86 que admiten la instrucción SYSENTER en modo de 64 bits son vulnerables. Se cree que son CPU de Intel, Centaur y Shanghai. No se cree que las CPU AMD e Hygon sean vulnerables. Solo los invitados PV x86 pueden aprovechar la vulnerabilidad. Los invitados x86 PVH/HVM no pueden aprovechar la vulnerabilidad

*Credits: N/A

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2020-09-16 CVE Reserved
2020-09-23 CVE Published
2023-03-08 EPSS Updated
2024-08-04 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

CAPEC

References (7)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC
https://xenbits.xen.org/xsa/advisory-339.html	2023-11-07

URL	Date	SRC
http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00008.html	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4JRXMKEMQRQYWYEPHVBIWUEAVQ3LU4FN	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DA633Y3G5KX7MKRN4PFEGM3IVTJMBEOM	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RJZERRBJN6E6STDCHT4JHP4MI6TKBCJE	2023-11-07
https://security.gentoo.org/glsa/202011-06	2023-11-07
https://www.debian.org/security/2020/dsa-4769	2023-11-07

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Xen Search vendor "Xen"		Xen Search vendor "Xen" for product "Xen"				>= 3.2.0 <= 4.14.0 Search vendor "Xen" for product "Xen" and version " >= 3.2.0 <= 4.14.0"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				31 Search vendor "Fedoraproject" for product "Fedora" and version "31"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				32 Search vendor "Fedoraproject" for product "Fedora" and version "32"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				33 Search vendor "Fedoraproject" for product "Fedora" and version "33"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				10.0 Search vendor "Debian" for product "Debian Linux" and version "10.0"		-		Affected
Opensuse Search vendor "Opensuse"		Leap Search vendor "Opensuse" for product "Leap"				15.2 Search vendor "Opensuse" for product "Leap" and version "15.2"		-		Affected