insufficient grant unmapping checks for x86 PV guests

2017-09-1212:00:00

Xen Project

xenbits.xen.org

501

8.8 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

7.2 High

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

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

0.001 Low

EPSS

Percentile

25.6%

JSON

ISSUE DESCRIPTION

When removing or replacing a grant mapping, the x86 PV specific path needs to make sure page table entries remain in sync with other accounting done. Although the identity of the page frame was validated correctly, neither the presence of the mapping nor page writability were taken into account.

IMPACT

A malicious or buggy x86 PV guest could escalate its privileges or crash the hypervisor.

VULNERABLE SYSTEMS

All Xen versions are affected.
Only x86 PV guests can leverage the vulnerability. x86 HVM guests as well as ARM guests cannot leverage the vulnerability.