SMTP Mail <= 1.3.42 is vulnerable to Unauthenticated Stored Cross-Site Scripting via Email Subject vulnerability

The SMTP Mail plugin for WordPress is vulnerable to Stored Cross-Site Scripting via an email subject in versions up to, and including, 1.3.42 due to insufficient input sanitization and output escaping when the 'Save Data SendMail' feature is enabled. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.