Database/Kernel, userspace & hypervisor
Xen - x86 PV guest denial of service via SYSENTER: SYSENTER leaves state sanitisation to software, and on AMD hardware
CVE-2020-25596Kernel, userspace & hypervisorcurated
Impact
SYSENTER leaves state sanitisation to software, and on AMD hardware Xen's PV guest handling got it wrong, letting a PV guest kernel deny service to itself and destabilise the host path. Legacy PV territory, included for completeness of the Xen-on-AMD picture.
Who can reach it
From inside an x86 PV guest.
What to do
Fixed in Xen (XSA-339). Hypervisor update plus host reboot. The durable answer is to stop running PV guests - HVM/PVH is the supported path and carries less of this legacy surface.
References
This entry is curated: imported from vendor advisories with machine assistance, not yet individually verified. Confirm against your vendor's advisory before acting, and report anything wrong.