The htmlspecialchars function in PHP before 5.2.12 does not properly handle (1) overlong UTF-8 sequences, (2) invalid Shift_JIS sequences, and (3) invalid EUC-JP sequences, which allows remote attackers to conduct cross-site scripting (XSS) attacks by placing a crafted byte sequence before a special character.
bugs.php.net/bug.php?id=49785
lists.apple.com/archives/security-announce/2010//Mar/msg00001.html
marc.info/?l=bugtraq&m=127680701405735&w=2
secunia.com/advisories/37821
secunia.com/advisories/38648
secunia.com/advisories/40262
securitytracker.com/id?1023372
support.apple.com/kb/HT4077
www.debian.org/security/2010/dsa-2001
www.php.net/ChangeLog-5.php
www.php.net/releases/5_2_12.php
www.securityfocus.com/bid/37389
www.vupen.com/english/advisories/2009/3593
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10005
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7085