pcap_ether_aton() is an auxiliary function in libpcap, it takes a string argument and returns a fixed-size allocated buffer.  The string argument must be a well-formed MAC-48 address in one of the supported formats, but this requirement has been poorly documented.  If an application calls the function with an argument that deviates from the expected format, the function can read data beyond the end of the provided string and write data beyond the end of the allocated buffer.