x86 PV guests may be able to mask interrupts

2016-12-2112:00:00

Xen Project

xenbits.xen.org

6 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

HIGH

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

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

4.9 Medium

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:N/I:N/A:C

0.001 Low

EPSS

Percentile

25.7%

JSON

ISSUE DESCRIPTION

Certain PV guest kernel operations (page table writes in particular) need emulation, and use Xen’s general x86 instruction emulator. This allows a malicious guest kernel which asynchronously modifies its instruction stream to effect the clearing of EFLAGS.IF from the state used to return to guest context.

IMPACT

A malicious guest kernel administrator can cause a host hang or crash, resulting in a Denial of Service.

VULNERABLE SYSTEMS

All Xen versions are vulnerable.
Only x86 PV guests can exploit the vulnerability.
Neither ARM guests nor x86 HVM guests can exploit the vulnerability.