HTML Injection in Post Grid WordPress Plugin

Executive Summary

The Post Grid WordPress plugin before version 7.9.5 improperly expands the WordPress allowed-HTML list site-wide instead of restricting it to its own markup. This allows users with Contributor role or higher to inject malicious iframe, style, and input elements into content. These elements bypass normal sanitization, enabling HTML injection attacks such as phishing frames, CSS defacement, and spoofed input forms.

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Detection Guidance

Check the installed version of the Post Grid plugin in WordPress. If it is below 7.9.5, the system is vulnerable. Use WordPress admin dashboard or run SQL query on the database: SELECT * FROM wp_options WHERE option_name LIKE '%post_grid_version%';

Inspect WordPress posts or pages for unexpected iframe, style, or input HTML tags in the content. Use grep to search for suspicious patterns in files: grep -r '<iframe' /path/to/wordpress/wp-content/

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Impact Analysis

Visitors and administrators viewing compromised content may encounter phishing attempts through malicious iframes, CSS defacement altering site appearance, or fake input forms designed to steal user data. The injected content renders to all users, potentially compromising site integrity and user trust.

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Compliance Impact

This vulnerability could lead to data breaches or unauthorized content modifications, violating GDPR's integrity and confidentiality requirements or HIPAA's safeguards for protected health information. Organizations may face compliance penalties if user data is exposed through injected malicious content.

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Mitigation Strategies

Update the Post Grid plugin to version 7.9.5 or later immediately. Disable the plugin temporarily if an update is not immediately available. Review all user roles with Contributor access or higher for unauthorized content changes.

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