5.6 Medium
CVSS3
Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H
4.7 Medium
CVSS2
Access Vector
LOCAL
Access Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:L/AC:M/Au:N/C:N/I:N/A:C
0.001 Low
EPSS
Percentile
24.9%
The INVPCID instruction raises #GP[0] if an attempt is made to invalidate a non-canonical address. Older flushing mechanisms such as INVLPG tolerate this without error, and perform no action.
There is one guest accessible path in Xen where a non-canonical address was passed into the TLB flushing code. This previously had no ill effect, but became vulnerable with the introduction of PCID to reduce the performance hit from the Meltdown mitigations.
A buggy or malicious PV guest can crash the host.
Only hardware which supports the INVPCID instruction is vulnerable. This is available on Intel Haswell processors and later. AMD x86 processors are not known to support this instruction, and ARM processors are entirely unaffected.
Only versions of Xen with PCID support are vulnerable. Support first appeared in Xen 4.11 but was backported to the stable trees as part of the Meltdown (XSA-254 / CVE-2017-5754) fixes. Xen 4.10.2, 4.9.3, 4.8.4 as well as the stable-4.7 and 4.6 branches are vulnerable.
The vulnerability is only exposed to 64-bit PV guests. 32-bit PV guests, as well as HVM/PVH guests cannot exploit the vulnerability.
5.6 Medium
CVSS3
Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H
4.7 Medium
CVSS2
Access Vector
LOCAL
Access Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
COMPLETE
AV:L/AC:M/Au:N/C:N/I:N/A:C
0.001 Low
EPSS
Percentile
24.9%