Description
WordPress Plugin Email Subscribers by Icegram Express-Email Marketing, Newsletters, Automation for WordPress & WooCommerce is prone to a security bypass vulnerability. Exploiting this issue may allow attackers to perform otherwise restricted actions and subsequently bypass the subscription form using fake email accounts. WordPress Plugin Email Subscribers by Icegram Express-Email Marketing, Newsletters, Automation for WordPress & WooCommerce version 3.5.13 is vulnerable; prior versions may also be affected.
Remediation
Update to plugin version 3.5.14 or latest
References
https://wordpress.org/support/topic/russian-spam-is-back-again/
https://plugins.svn.wordpress.org/email-subscribers/trunk/readme.txt