An exploitable vulnerability exists in the verified boot protection of the Das U-Boot from version 2013.07-rc1 to 2014.07-rc2. The affected versions lack proper FIT signature enforcement, which allows an attacker to bypass U-Boot’s verified boot and execute an unsigned kernel, embedded in a legacy image format. To trigger this vulnerability, a local attacker needs to be able to supply the image to boot.
Source: NIST