The utf8_decode function in PHP before 5.3.4 does not properly handle non-shortest form UTF-8 encoding and ill-formed subsequences in UTF-8 data, which makes it easier for remote attackers to bypass cross-site scripting (XSS) and SQL injection protection mechanisms via a crafted string.
http://www.vupen.com/english/advisories/2011/0077
http://www.vupen.com/english/advisories/2011/0021
http://www.vupen.com/english/advisories/2011/0020
http://www.vupen.com/english/advisories/2010/3081
http://www.ubuntu.com/usn/USN-1042-1
http://www.securitytracker.com/id?1024797
http://www.securityfocus.com/bid/44605
http://www.redhat.com/support/errata/RHSA-2011-0195.html
http://www.redhat.com/support/errata/RHSA-2010-0919.html
http://www.php.net/ChangeLog-5.php
http://www.openwall.com/lists/oss-security/2010/11/03/1
http://www.openwall.com/lists/oss-security/2010/11/02/8
http://www.openwall.com/lists/oss-security/2010/11/02/6
http://www.openwall.com/lists/oss-security/2010/11/02/4
http://www.openwall.com/lists/oss-security/2010/11/02/2
http://www.openwall.com/lists/oss-security/2010/11/02/11
http://www.openwall.com/lists/oss-security/2010/11/02/1
http://www.mandriva.com/en/security/advisories?name=MDVSA-2010:224
http://svn.php.net/viewvc?view=revision&revision=304959
http://support.apple.com/kb/HT4581
http://secunia.com/advisories/42812
http://secunia.com/advisories/42410
http://marc.info/?l=bugtraq&m=133469208622507&w=2
http://lists.opensuse.org/opensuse-security-announce/2010-12/msg00000.html
http://lists.fedoraproject.org/pipermail/package-announce/2011-January/052845.html
http://lists.fedoraproject.org/pipermail/package-announce/2011-January/052836.html
http://lists.apple.com/archives/security-announce/2011/Mar/msg00006.html