Multiple cross-site scripting (XSS) vulnerabilities in wp-login.php in the Register Plus plugin 3.5.1 and earlier for WordPress allow remote attackers to inject arbitrary web script or HTML via the (1) firstname, (2) lastname, (3) website, (4) aim, (5) yahoo, (6) jabber, (7) about, (8) pass1, and (9) pass2 parameters in a register action.