CVE-2021-34667: Calendar Plugin Project Calendar Plugin

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

The Calendar_plugin WordPress plugin is vulnerable to Reflected Cross-Site Scripting due to the use of `$_SERVER['PHP_SELF']` in the ~/calendar.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 1.0.

Affected products

• Calendar Plugin Project Calendar Plugin: up to and including 1.0

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