The Mitsol Social Post Feed plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 1.10 due to insufficient input sanitization and output escaping on the application id parameters. This makes it possible for authenticated (admin+) attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html is disabled.