CVE-2019-18420

Current Description

An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to cause a denial of service via a VCPUOP_initialise hypercall. hypercall_create_continuation() is a variadic function which uses a printf-like format string to interpret its parameters. Error handling for a bad format character was done using BUG(), which crashes Xen. One path, via the VCPUOP_initialise hypercall, has a bad format character. The BUG() can be hit if VCPUOP_initialise executes for a sufficiently long period of time for a continuation to be created. Malicious guests may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen versions 4.6 and newer are vulnerable. Xen versions 4.5 and earlier are not vulnerable. Only x86 PV guests can exploit the vulnerability. HVM and PVH guests, and guests on ARM systems, cannot exploit the vulnerability.

Basic Data

Published	October 31, 2019
Last Modified	November 14, 2019
Assigner	cve@mitre.org
Data Type	CVE
Data Format	MITRE
Data Version	4.0
Problem Type	CWE-20
CVE Data Version	4.0

Base Metric V2

CVSS 2 - Version	2.0
CVSS 2 - Vector String	AV:N/AC:M/Au:S/C:N/I:N/A:C
CVSS 2 - Access Vector	NETWORK
CVSS 2 - Access Complexity	MEDIUM
CVSS 2 - Authentication	SINGLE
CVSS 2 - Confidentiality Impact	NONE
CVSS 2 - Availability Impact	COMPLETE
CVSS 2 - Base Score	6.3
Severity	MEDIUM
Exploitability Score	6.8
Impact Score	6.9
Obtain All Privilege	false
Obtain User Privilege	false
Obtain Other Privilege	false

Base Metric V3

No data provided.

Configurations

Vulnerable Software List

Vendor	Product	Versions
Xen	Xen	*

References