The exec_dir PHP patch (php-exec-dir) 4.3.2 through 4.3.7 with safe mode disabled allows remote attackers to bypass restrictions and execute arbitrary commands via a backtick operator, which is not handled using the php_escape_shell_cmd function.
kyberdigi.cz/projects/execdir/english.html
seclists.org/fulldisclosure/2004/Jul/0347.html
seclists.org/fulldisclosure/2004/Jul/0350.html
seclists.org/fulldisclosure/2004/Jul/0357.html
secunia.com/advisories/11928
www.osvdb.org/7243
www.securityfocus.com/bid/10598
exchange.xforce.ibmcloud.com/vulnerabilities/16498