A bug in QEMU could cause a guest I/O operation otherwise addressed to an arbitrary disk offset to be targeted to offset 0 instead (potentially overwriting the VM's boot code). This could be used, for example, by L2 guests with a virtual disk (vdiskL2) stored on a virtual disk of an L1 (vdiskL1) hypervisor to read and/or write data to LBA 0 of vdiskL1, potentially gaining control of L1 at its next reboot.
https://lore.kernel.org/all/[email protected]/T/
https://bugzilla.redhat.com/show_bug.cgi?id=2247283
https://access.redhat.com/security/cve/CVE-2023-5088