CVE-2026-4658
Deferred Deferred - Pending Action
Stored XSS in Essential Blocks WordPress Plugin

Publication date: 2026-05-02

Last updated on: 2026-05-05

Assigner: Wordfence

Description
The Essential Blocks – Page Builder Gutenberg Blocks, Patterns & Templates plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the className, classHook, and blockId attributes in the Add to Cart block (essential-blocks/add-to-cart) in all versions up to, and including, 6.0.4. This is due to insufficient output escaping in the render_callback() function where these attributes are placed into class and data-id HTML attributes using raw sprintf() and implode() without esc_attr() escaping. While the outer wrapper div uses get_block_wrapper_attributes() which properly escapes, the inner divs do not. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Meta Information
Published
2026-05-02
Last Modified
2026-05-05
Generated
2026-06-16
AI Q&A
2026-05-02
EPSS Evaluated
2026-06-15
NVD
CVE-2026-4658
EUVD
EUVD-2026-26733
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
essential_blocks page_builder_gutenberg_blocks_patterns_templates to 6.0.4 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
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Impact Analysis

This vulnerability allows attackers with Contributor-level access or above to inject malicious scripts into pages via the Add to Cart block.

When other users visit these pages, the injected scripts execute in their browsers, potentially leading to theft of sensitive information, session hijacking, or other malicious actions.

The impact includes loss of data integrity and confidentiality, and it may compromise user trust and site security.

Executive Summary

The vulnerability exists in the Essential Blocks – Page Builder Gutenberg Blocks, Patterns & Templates plugin for WordPress, specifically in the Add to Cart block (essential-blocks/add-to-cart) in all versions up to and including 6.0.4.

It is a Stored Cross-Site Scripting (XSS) vulnerability caused by insufficient output escaping in the render_callback() function. The className, classHook, and blockId attributes are inserted into class and data-id HTML attributes using raw sprintf() and implode() functions without proper escaping (esc_attr()).

While the outer wrapper div is properly escaped, the inner divs are not, allowing authenticated attackers with Contributor-level access or higher to inject arbitrary web scripts. These scripts execute whenever a user accesses the injected page.

Compliance Impact

The vulnerability allows authenticated attackers with Contributor-level access and above to inject arbitrary web scripts via Stored Cross-Site Scripting (XSS) in pages. This can lead to unauthorized access or manipulation of user data when users access the injected pages.

Such unauthorized script execution can potentially compromise the confidentiality and integrity of user data, which may impact compliance with data protection regulations like GDPR and HIPAA that require safeguarding personal and sensitive information against unauthorized access or disclosure.

However, the provided information does not explicitly detail the direct compliance impact or specific regulatory implications of this vulnerability.

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