Azure RTOS USBx is a USB host, device, and on-the-go (OTG) embedded stack, fully integrated with Azure RTOS ThreadX and available for all Azure RTOS ThreadX-supported processors. Azure RTOS USBX implementation of host support for USB CDC ECM includes an integer underflow and a buffer overflow in the _ux_host_class_cdc_ecm_mac_address_get function which may be potentially exploited to achieve remote code execution or denial of service. Setting mac address string descriptor length to a 0 or 1 allows an attacker to introduce an integer underflow followed (string_length) by a buffer overflow of the cdc_ecm - ux_host_class_cdc_ecm_node_id array.

This may allow one to redirect the code execution flow or introduce a denial of service. The fix has been included in USBX release 6.1.12. Improved mac address string descriptor length validation to check for unexpectedly small values may be used as a workaround.