CVE-2021-34658: Keszites Simple Popup Newsletter

Medium severity, CVSS 6.1. EPSS: 0.9% chance of exploitation in the next 30 days.

The Simple Popup Newsletter WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of $_SERVER['PHP_SELF'] in the ~/simple-popup-newsletter.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 1.4.7.

Affected products

• Keszites Simple Popup Newsletter: up to and including 1.4.7

Published 2021-08-16. Last modified 2026-06-17.