fopen_wrappers.c in PHP 4.4.0, and possibly other versions, does not properly restrict access to other directories when the open_basedir directive includes a trailing slash, which allows PHP scripts in one directory to access files in other directories whose names are substrings of the original directory.
bugs.debian.org/cgi-bin/bugreport.cgi?bug=323585
lists.trustix.org/pipermail/tsl-announce/2005-October/000354.html
secunia.com/advisories/17229
secunia.com/advisories/17371
secunia.com/advisories/17510
secunia.com/advisories/17557
www.gentoo.org/security/en/glsa/glsa-200511-08.xml
www.mandriva.com/security/advisories?name=MDKSA-2005:213
www.php.net/release_4_4_1.php
www.securityfocus.com/bid/14957
www.vupen.com/english/advisories/2005/1862
www.vupen.com/english/advisories/2005/2254
usn.ubuntu.com/207-1/