CVE-2025-58151

[Support]

CVE-2025-58151
varstored is a component of the Xapi toolstack handling UEFI Variables
for a VM. It has a communication path with OVMF inside the VM involving
mapping a buffer prepared by OVMF.

Within varstored, there were insufficient compiler barriers, creating
TOCTOU issues with data in the shared buffer.

The exact vulnerable behaviour depends on the code generated by the
compiler. In a build of varstored using default settings, the attacker
can control an index used in a jump table.