The session extension in PHP before 5.2.4 might allow local users to bypass open_basedir restrictions via a session file that is a symlink.
secunia.com/advisories/26642
secunia.com/advisories/26822
secunia.com/advisories/26838
secunia.com/advisories/27102
secunia.com/advisories/27377
www.gentoo.org/security/en/glsa/glsa-200710-02.xml
www.php.net/ChangeLog-5.php#5.2.4
www.php.net/releases/5_2_4.php
www.trustix.org/errata/2007/0026/
www.vupen.com/english/advisories/2007/3023
exchange.xforce.ibmcloud.com/vulnerabilities/36387
issues.rpath.com/browse/RPL-1693
issues.rpath.com/browse/RPL-1702