Double SSH

#!/bin/bash

set -ex

# I am on server A
sshpass -e ssh -o PubkeyAuthentication=no -o StrictHostKeyChecking=no "${SSH_USERNAME}@${SERVER_B}" <<EOF
  # Now I am on server B
  export SSH_USERNAME=$SSH_USERNAME  # Copy env. variable from server A to server B
  export SERVER_C=$SERVER_C          # Copy env. variable from server A to server B
  export SSHPASS=$SSHPASS            # INSECURE!! copy env. variable from server A to server B
  sshpass -e ssh -o PubkeyAuthentication=no -o StrictHostKeyChecking=no "${SSH_USERNAME}@${SERVER_C}" <<EOF2
    # Now I am on server C
EOF2  
EOF