MLdonkey (up to 2.9.7) has  a  vulnerability  that allows remote user to access any
file   with   rights   of  running  Mldonkey  daemon  by  supplying  a
special-crafted  request  (ok,  there's  not much special about double
slash) to an Mldonkey http GUI (tcp/4080 usually).

Reference:
https://savannah.nongnu.org/bugs/?25667

Thus, the exploit would be as simple as accessing any file on a remote
host with your browser and double slash:

http://mlhost:4080//etc/passwd

# milw0rm.com [2009-02-23]