An out-of-bounds memory access flaw, leading to memory corruption or possibly an information leak, was found in QEMU's pit_ioport_read() function. A privileged guest user in a QEMU guest, which had QEMU PIT emulation enabled, could potentially, in rare cases, use this flaw to execute arbitrary code on the host with the privileges of the hosting QEMU process.
A heap overflow flaw was found in the way QEMU's IDE subsystem handled I/O buffer access while processing certain ATAPI commands. A privileged guest user in a guest with CDROM drive enabled could potentially use this flaw to execute arbitrary code on the host with the privileges of the host's QEMU process corresponding to the guest.
This is a guest-triggerable buffer overflow. The scsi_cdb_length returns -1 as an error value, but the caller does not check it. Luckily, the massive overflow means that QEMU will just SIGSEGV, leading to denial of service of the guest system.