7.8 High
CVSS3
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
0.0004 Low
EPSS
Percentile
9.2%
For migration as well as to work around kernels unaware of L1TF (see XSA-273), PV guests may be run in shadow paging mode. Since Xen itself needs to be mapped when PV guests run, Xen and shadowed PV guests run directly the respective shadow page tables. For 64-bit PV guests this means running on the shadow of the guest root page table.
In the course of dealing with shortage of memory in the shadow pool associated with a domain, shadows of page tables may be torn down. This tearing down may include the shadow root page table that the CPU in question is presently running on. While a precaution exists to supposedly prevent the tearing down of the underlying live page table, the time window covered by that precaution isn’t large enough.
Privilege escalation, Denial of Service (DoS) affecting the entire host, and information leaks all cannot be ruled out.
All Xen versions from at least 3.2 onwards are vulnerable. Earlier versions have not been inspected.
Only x86 systems are vulnerable. Only 64-bit PV guests can leverage the vulnerability, and only when running in shadow mode. Shadow mode would be in use when migrating guests or as a workaround for XSA-273 (L1TF).