Get Youtube Subs <= 3.5 - Authenticated (Contributor+) Stored Cross-Site Scripting via subscribe_link_att Function

The Get Youtube Subs plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘channel', 'layout', and 'subs_count’ parameters in all versions up to, and including, 3.5 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.