CVE-2021-34658: Simple Popup Newsletter <= 1.4.7 Reflected Cross-Site Scripting

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-08-16 · updated 2026-06-17
Weakness: CWE-79

Description

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

Simple Popup Newsletter: through 1.4.7

References

https://plugins.trac.wordpress.org/browser/simple-popup-newsletter/trunk/simple-popup-newsletter.php#L319
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-34658
https://plugins.trac.wordpress.org/browser/simple-popup-newsletter/trunk/simple-popup-newsletter.php#L319
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-34658

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