Executive Summary

The YayMail - WooCommerce Email Customizer plugin for WordPress has a vulnerability that allows unauthorized plugin installation and activation. This happens because the plugin does not properly check user capabilities on certain AJAX and REST API endpoints, specifically the 'yaymail_install_yaysmtp' AJAX action and the '/yaymail/v1/addons/activate' REST endpoint.

As a result, any authenticated user with Shop Manager-level access or higher can exploit this flaw to install and activate the YaySMTP plugin without proper authorization.

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Impact Analysis

This vulnerability can impact you by allowing users with Shop Manager-level access or above to install and activate plugins without proper permission checks. This could lead to unauthorized changes to your WordPress environment.

Specifically, an attacker could install and activate the YaySMTP plugin, potentially altering email sending behavior or introducing additional attack vectors through the newly installed plugin.

Although the CVSS base score is relatively low (2.7), indicating limited impact on confidentiality and availability, the integrity of your site could be compromised by unauthorized plugin activation.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability involves unauthorized installation and activation of the YaySMTP plugin via the 'yaymail_install_yaysmtp' AJAX action and the '/yaymail/v1/addons/activate' REST endpoint. Detection can focus on monitoring for suspicious AJAX requests or REST API calls related to these endpoints."}, {'type': 'list_item', 'content': "Check web server or application logs for POST requests to the AJAX action 'yaymail_install_yaysmtp' or REST endpoint '/wp-json/yaymail/v1/addons/activate'."}, {'type': 'list_item', 'content': 'Look for unexpected plugin installation or activation events in WordPress logs or audit trails.'}, {'type': 'list_item', 'content': "Use commands like `grep 'yaymail_install_yaysmtp' /path/to/access.log` or `grep '/wp-json/yaymail/v1/addons/activate' /path/to/access.log` to find relevant HTTP requests."}, {'type': 'list_item', 'content': 'Monitor WordPress plugin directories for new files or changes related to the YaySMTP plugin.'}] [1, 3, 4]

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Mitigation Strategies

Immediate mitigation steps include restricting access to the vulnerable AJAX and REST endpoints and limiting user capabilities.

• Restrict or disable the 'yaymail_install_yaysmtp' AJAX action and the '/yaymail/v1/addons/activate' REST endpoint if possible, for example by blocking these URLs at the web server or firewall level.
• Limit Shop Manager-level and higher user permissions to trusted users only, as the vulnerability requires authenticated users with such access.
• Update the YayMail plugin to a version later than 4.3.2 where this vulnerability is fixed.
• Monitor plugin installations and activations closely to detect any unauthorized activity.

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