A use-after-free flaw was found in the OHCI USB host controller emulation (hw/usb/hcd-ohci.c) in QEMU. When an isochronous transfer descriptor is directed at a non-isochronous endpoint, ohci_service_iso_td() can free a heap-allocated USBPacket while a pending asynchronous transfer still holds a reference to it; that reference is later dereferenced when the transfer completes. A malicious guest able to program the emulated OHCI controller can use this to crash the QEMU process on the host (denial of service) and potentially execute arbitrary code in the context of the QEMU process. The issue is fixed in QEMU 11.1.3 and 10.0.15.