The file upload capability in PHP versions 3 and 4 allows remote attackers to read arbitrary files by setting hidden form fields whose names match the names of internal PHP script variables.
archives.neohapsis.com/archives/bugtraq/2000-08/0455.html
archives.neohapsis.com/archives/bugtraq/2000-08/0477.html
archives.neohapsis.com/archives/bugtraq/2000-09/0150.html
cvsweb.php.net/viewcvs.cgi/php4/main/rfc1867.c.diff?r1=1.38%3Aphp_4_0_2&tr1=1.1&r2=text&tr2=1.45&diff_format=u
www.securityfocus.com/bid/1649
exchange.xforce.ibmcloud.com/vulnerabilities/5190