Kirby CMS 2.5.7 - Cross-Site Scripting

# Exploit Title: KirbyCMS <2.5.7 Stored Cross Site Scripting
# Vendor Homepage: https://getkirby.com/
# Software Link: https://getkirby.com/try
# Discovered by: Ishaq Mohammed
# Contact: https://twitter.com/security_prince
# Website: https://about.me/security-prince
# Category: webapps
# Platform: PHP
# CVE: CVE-2017-16807

1. Description
   
A cross-site Scripting (XSS) vulnerability in Kirby Panel before 2.3.3, 2.4.x before 2.4.2, and 2.5.x before 2.5.7 exists when displaying a specially prepared SVG document that has been uploaded as a content file.

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-16807

2. Proof of Concept

Steps to Reproduce:
Log in as an Editor and click on Site Options
Add the malicious .svg file which contains the javascript to the Site
Login to another browser with Admin Credentials.
Click on Site Options.
Click on the newly added .svg file

3. Reference

https://securityprince.blogspot.in/2017/11/cve-2017-16807-kirby-cms-257-cross-site.html   
https://getkirby.com/changelog/kirby-2-5-7

4. Solution

The vulnerability is patched by the vendor in the version 2.5.7.