DENX U-Boot through 2018.09-rc1 has a remotely exploitable buffer overflow via a malicious TFTP server because TFTP traffic is mishandled. Also, local exploitation can occur via a crafted kernel image.
U-Boot contains a CWE-20: Improper Input Validation vulnerability in Verified boot signature validation that can result in Bypass verified boot. This attack appear to be exploitable via Specially crafted FIT image and special device memory functionality.