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.
bugs.php.net/bug.php?id=41492
lists.opensuse.org/opensuse-security-announce/2007-07/msg00006.html
osvdb.org/36084
secunia.com/advisories/25456
secunia.com/advisories/26048
secunia.com/advisories/26231
secunia.com/advisories/27102
secunia.com/advisories/27110
www.gentoo.org/security/en/glsa/glsa-200710-02.xml
www.php.net/releases/5_2_3.php
www.securityfocus.com/bid/24259
www.trustix.org/errata/2007/0023/
www.redhat.com/archives/fedora-package-announce/2007-September/msg00397.html