PHP 5 before 5.2.7 does not properly initialize the page_uid and page_gid global variables for use by the SAPI php_getuid function, which allows context-dependent attackers to bypass safe_mode restrictions via variable settings that are intended to be restricted to root, as demonstrated by a setting of /etc for the error_log variable.
https://exchange.xforce.ibmcloud.com/vulnerabilities/47318
http://www.securityfocus.com/bid/32688
http://www.securityfocus.com/archive/1/501376/100/0/threaded
http://www.securityfocus.com/archive/1/498985/100/0/threaded
http://www.php.net/ChangeLog-5.php#5.2.7
http://www.mandriva.com/security/advisories?name=MDVSA-2009:045
http://www.debian.org/security/2009/dsa-1789
http://wiki.rpath.com/Advisories:rPSA-2009-0035
http://secunia.com/advisories/35650
http://secunia.com/advisories/35003