The GoSMTP Pro plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Content via Email Log Body in all versions up to, and including, 1.2.3 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. The exploit is made possible because WordPress comment kses does not strip entity-encoded tag delimiters, allowing the payload to pass moderation as safe text before being decoded into live HTML by core email notification functions and written verbatim into the plugin's email log database table.