fdctrl_write_data in hw/block/fdc.c in QEMU 5.0.0 has a NULL pointer dereference via a NULL block pointer for the current drive.
https://security.netapp.com/advisory/ntap-20201009-0005/
https://ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Ffdc_nullptr1
https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg05295.html