The Listen Shortcode plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'listen' shortcode in versions up to, and including, 1.0. This is due to insufficient input sanitization and output escaping on user supplied attributes (src, start, end) in the listenEmbedJS() function, which are echoed inside a single-quoted HTML attribute without 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.