Firmware updates at an information handling system flash memory device, such as provisioning information stored on a USB device, are securely performed by using a buffer memory and a secured code. An application running on a CPU generates a firmware update and a security code, such as a ciphered hash code based on the firmware update, stores the firmware update and security code in a buffer, and informs a management processor of the update. The management processor analyzes the firmware update to authorize copying of the update from the buffer to the flash memory device. For instance, the management processor creates the security code from the firmware update and compares the created code with the security code stored in the buffer to validate the firmware update.