FluentSMTP < 2.3.0 - Unauthenticated Stored XSS via Recipient Display Name in Email Logs

Description

The plugin is vulnerable to Stored Cross-Site Scripting via the Recipient Display Name (to.name) in Email Logs 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 payload is delivered via an attacker-controlled recipient display name (to.name) in a wp_mail() call and does not fire in the log list view — only in the detail view when an administrator uses the Prev/Next navigation controls, as that path bypasses the escapeHtml pipeline used by the list view.