SQL injection vulnerability in ProFTPD Server 1.3.1 through 1.3.2rc2 allows remote attackers to execute arbitrary SQL commands via a "%" (percent) character in the username, which introduces a "'" (single quote) character during variable substitution by mod_sql.
http://secunia.com/advisories/34268
http://security.gentoo.org/glsa/glsa-200903-27.xml
https://www.exploit-db.com/exploits/8037
http://www.debian.org/security/2009/dsa-1730
http://www.mandriva.com/security/advisories?name=MDVSA-2009:061
http://www.openwall.com/lists/oss-security/2009/02/11/1