util-linux/mdev.c in BusyBox before 1.21.0 uses 0777 permissions for parent directories when creating nested directories under /dev/, which allows local users to have unknown impact and attack vectors.
The DHCP client (udhcpc) in BusyBox before 1.20.0 allows remote DHCP servers to execute arbitrary commands via shell metacharacters in the (1) HOST_NAME, (2) DOMAIN_NAME, (3) NIS_DOMAIN, and (4) TFTP_SERVER_NAME host name options.