OptinMonster <= 2.6.4 - Unprotected REST-API Endpoints

Improper Authorization
CVE CVE-2021-39341
CVSS 8.2 (High)
Publicly Published November 1, 2021
Last Updated February 3, 2023
Researcher Chloe Chamberland - Wordfence


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.

Wordfence blocked 18,244 attacks targeting this vulnerability in the past 24 hours.



Vulnerability Details for Popup Builder by OptinMonster – WordPress Popups for Optins, Email Newsletters and Lead Generation

Software Type Plugin
Software Slug optinmonster (view on wordpress.org)
Patched? Yes
Remediation Update to version 2.6.5, or a newer patched version
Affected Version
  • <= 2.6.4
Patched Version
  • 2.6.5

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