CVE-2024-4891 in Essential Blocks Plugin
Summary
by MITRE • 05/18/2024
The Essential Blocks – Page Builder Gutenberg Blocks, Patterns & Templates plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘tagName’ parameter in versions up to, and including, 4.5.12 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 03/29/2025
The Essential Blocks plugin for WordPress represents a popular suite of gutenberg blocks, patterns, and templates designed to enhance content creation capabilities for wordpress users. This plugin has been identified with a critical stored cross-site scripting vulnerability that affects versions up to and including 4.5.12. The vulnerability stems from inadequate input sanitization and output escaping mechanisms within the plugin's codebase, specifically in how it handles the 'tagName' parameter. This flaw creates a significant security risk for wordpress installations that utilize this plugin, particularly in environments where multiple user roles exist with varying permission levels.
The technical implementation of this vulnerability occurs within the plugin's handling of user input through the 'tagName' parameter which is processed without proper sanitization measures. When authenticated attackers with contributor-level permissions or higher submit malicious input through this parameter, the system fails to adequately escape or validate the data before storing it in the database. This stored data then executes whenever any user accesses pages containing the malicious script, creating a persistent threat vector that can affect any user role within the wordpress installation. The vulnerability follows the CWE-79 pattern of cross-site scripting, specifically manifesting as a stored XSS attack where malicious payloads are permanently stored on the server rather than being reflected in a single request.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to potentially escalate their privileges and compromise entire wordpress installations. Contributors and higher-level users can inject malicious javascript that executes in the context of other users' browsers, potentially allowing for session hijacking, data exfiltration, or further exploitation of the wordpress environment. The stored nature of the vulnerability means that the malicious scripts persist indefinitely until manually removed, creating a long-term threat that can affect all users who view affected pages. This vulnerability particularly impacts wordpress sites where multiple contributors or editors have access, as it requires only basic contributor permissions to exploit, making it accessible to users who should normally have limited administrative capabilities.
Mitigation strategies for this vulnerability should include immediate plugin updates to versions that address the XSS flaw, which aligns with standard security practices outlined in the mitre ATT&CK framework for web application vulnerabilities. Organizations should implement comprehensive input validation and output escaping mechanisms throughout their wordpress installations, ensuring that all user-supplied data is properly sanitized before storage. Network segmentation and user permission reviews should be conducted to minimize potential attack surfaces, while regular security audits of installed plugins can help identify similar vulnerabilities. Additionally, implementing content security policies and regular security monitoring can provide additional layers of protection against exploitation of similar stored XSS vulnerabilities in wordpress environments.