The fyyd podcast shortcodes plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'fyyd-podcast', 'fyyd-episode', and 'fyyd' shortcodes in all versions up to, and including, 0.3.1. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes such as 'color', 'podcast_id', and 'podcast_slug'. These attributes are directly concatenated into inline JavaScript within single-quoted string arguments without any escaping or sanitization, allowing an attacker to break out of the JavaScript string context. 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.