sapi/cgi/cgi_main.c in PHP before 5.3.13 and 5.4.x before 5.4.3, when
configured as a CGI script (aka php-cgi), does not properly handle query
strings that contain a %3D sequence but no = (equals sign) character, which
allows remote attackers to execute arbitrary code by placing command-line
options in the query string, related to lack of skipping a certain
php_getopt for the 'd' case. NOTE: this vulnerability exists because of an
incomplete fix for CVE-2012-1823.

It was discovered that PHP, when used as a stand alone CGI processor
for the Apache Web Server, did not properly parse and filter query
strings. This could allow a remote attacker to execute arbitrary code
running with the privilege of the web server. Configurations using
mod_php5 and FastCGI were not vulnerable.