Dell BIOS contain a Time-of-check Time-of-use vulnerability in BIOS. A local authenticated malicious user with physical access to the system could potentially exploit this vulnerability by using a specifically timed DMA transaction during an SMI in order to gain arbitrary code execution on the system.
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state.