PHP 5 before 5.2.3 does not enforce the open_basedir or safe_mode restriction in certain cases, which allows context-dependent attackers to determine the…

PHP 5 before 5.2.3 does not enforce the open_basedir or safe_mode restriction in certain cases, which allows context-dependent attackers to determine the existence of arbitrary files by checking if the readfile function returns a string. NOTE: this issue might also involve the realpath function.