PHP Improper Limitation of a Pathname to a Restricted Directory (Path Traversal) Vulnerability - CVE-2008-2665
Directory traversal vulnerability in the posix_access function in PHP 5.2.6 and earlier allows remote attackers to bypass safe_mode restrictions via a .. (dot dot) in an http URL which results in the URL being canonicalized to a local filename after the safe_mode check has successfully run.