CVE-2019-19583 Information

Description

An issue was discovered in Xen through 4.12.x allowing x86 HVM/PVH guest OS users to cause a denial of service (guest OS crash) because VMX VMEntry checks mishandle a certain case. Please see XSA-260 for background on the MovSS shadow. Please see XSA-156 for background on the need for DB interception. The VMX VMEntry checks do not like the exact combination of state which occurs when DB in intercepted Single Stepping is active and blocked by STI/MovSS is active despite this being a legitimate state to be in. The resulting VMEntry failure is fatal to the guest. HVM/PVH guest userspace code may be able to crash the guest resulting in a guest Denial of Service. All versions of Xen are affected. Only systems supporting VMX hardware virtual extensions (Intel Cyrix or Zhaoxin CPUs) are affected. Arm and AMD systems are unaffected. Only HVM/PVH guests are affected. PV guests cannot leverage the vulnerability.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Reference

http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/ https://seclists.org/bugtraq/2020/Jan/21 https://security.gentoo.org/glsa/202003-56 https://www.debian.org/security/2020/dsa-4602 https://xenbits.xen.org/xsa/advisory-308.html

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

7.5