SOGO Add Script to Individual Pages Header Footer <= 3.9 - Contributor+ Stored XSS via Post Metabox

The SOGO Add Script to Individual Pages Header Footer WordPress plugin through 3.9 does not sanitise or escape the custom header/footer script values saved from its post metabox, and does not restrict them to users with the unfiltered_html capability, allowing users with contributor-level access and above to store JavaScript that executes in the browser of any administrator who reviews the post and of any visitor once the post is published.