The POST SMTP Mailer WordPress plugin before 2.5.7 does not have proper CSRF checks in some AJAX actions, which could allow attackers to make logged in users with the managepostmansmtp capability resend an email to an arbitrary address (for example a password reset email could be resent to an attacker controlled email, and allow them to take over an account).

The POST SMTP Mailer plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.0.20. This is due to missing or incorrect nonce validation on the handleCsvExport() function. This makes it possible for unauthenticated attackers to trigger a CSV export via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

The Post SMTP plugin for WordPress is vulnerable to Stored Cross-Site Scripting via email contents in versions up to, and including, 2.5.7 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.