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:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H
EPSS
Percentile
14.2%
As part of XSA-226 a missing cleanup call was inserted on an error handling path. While doing so, locking requirements were not paid attention to. As a result two cooperating guests granting each other transitive grants can cause locks to be acquired nested within one another, but in respectively opposite order. With suitable timing between the involved grant copy operations this may result in the locking up of a CPU.
Malicious or buggy guest kernels may be able to mount a Denial of Service (DoS) attack affecting the entire system.
Xen versions 4.0 and newer are vulnerable. Xen versions 3.4 and older are not vulnerable.
Only guests with access to transitive grants can exploit the vulnerability. In particular, this means that:
gnttab=max-ver:1
or gnttab=no-transitive
are not vulnerable.max_grant_version=1
in their configuration file, ormax_grant_version=1
, and no guests have the default overridden by selecting max_grant_version=2
.