A vulnerability was found in xen, where a malicious or buggy HVM guest may cause the hypervisor to crash, resulting in Denial of Service (DoS) affecting the entire host.
Acknowledgments: Name: the Xen project
Statement: Xen versions 4.7 and earlier are not affected by this flaw. Arm systems are not affected, only x86 HVM guests using shadow paging can leverage the vulnerability. In addition there needs to be an entity actively monitoring a guest's video frame buffer (typically for display purposes) in order for such a guest to be able to leverage the vulnerability. x86 PV guests as well as x86 HVM guest using hardware assisted paging (HAP) cannot leverage the vulnerability.
Mitigation: For HVM guest explicitly configured to use shadow paging (e.g. via the `hap=0` xl domain configuration file parameter), changing to HAP (e.g. by setting `hap=1`) will avoid exposing the vulnerability to those guests. HAP is the default (in upstream Xen), where the hardware supports it; so this mitigation is only applicable if HAP has been disabled by configuration.
External References: https://xenbits.xen.org/xsa/advisory-319.html
Created xen tracking bugs for this issue: Affects: fedora-all [bug 1854463]
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2020-15563