WordPress before 2.0.6, when mbstring is enabled for PHP, decodes alternate character sets after escaping the SQL query, which allows remote attackers to bypass SQL injection protection schemes and execute arbitrary SQL commands via multibyte charsets, as demonstrated using UTF-7.
https://exchange.xforce.ibmcloud.com/vulnerabilities/31297
http://www.vupen.com/english/advisories/2007/0061
http://www.securityfocus.com/archive/1/456049/100/0/threaded
http://www.openpkg.com/security/advisories/OpenPKG-SA-2007.005.html
http://www.hardened-php.net/advisory_022007.141.html
http://wordpress.org/development/2007/01/wordpress-206/
http://securityreason.com/securityalert/2112
http://security.gentoo.org/glsa/glsa-200701-10.xml
http://secunia.com/advisories/23741