The Presto Player plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Content via <presto-player> Tag in all versions up to, and including, 4.5.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires an initial comment approval, though WordPress default settings will auto-approve all subsequent comments from the same author, allowing a patient unauthenticated attacker to land the payload without further admin intervention.