CVE-2021-3507: Improper Restriction of Operations within the Bounds of a Memory Buffer

A heap buffer overflow was found in the floppy disk emulator of QEMU up to 6.0.0 (including). It could occur in fdctrl_transfer_handler() in hw/block/fdc.c while processing DMA read data transfers from the floppy drive to the guest system. A privileged guest user could use this flaw to crash the QEMU process on the host resulting in DoS scenario, or potential information leakage from the host memory.