The get_option function in dhcp.c in dhcpcd before 6.2.0, as used in dhcpcd 5.x in Android before 5.1 and other products, does not validate the relationship between length fields and the amount of data, which allows remote DHCP servers to execute arbitrary code or cause a denial of service (memory corruption) via a large length value of an option in a DHCPACK message.
The get_option function in dhcpcd 4.0.0 through 6.x before 6.4.3 allows remote DHCP servers to cause a denial of service by resetting the DHO_OPTIONSOVERLOADED option in the (1) bootfile or (2) servername section, which triggers the option to be processed again.