CVE-2021-39341: Optinmonster

High severity, CVSS 8.2. EPSS: 21.9% chance of exploitation in the next 30 days.

The OptinMonster WordPress plugin is vulnerable to sensitive information disclosure and unauthorized setting updates due to insufficient authorization validation via the logged_in_or_has_api_key function in the ~/OMAPI/RestApi.php file that can used to exploit inject malicious web scripts on sites with the plugin installed. This affects versions up to, and including, 2.6.4.

Affected products

• Optinmonster Optinmonster: up to and including 2.6.4

Published 2021-11-01. Last modified 2026-06-17.