What the vulnerability does
01Description
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.
Explanation of Vulnerability in Simple Terms
02Summary
Gutenberg Essential Blocks versions up to 6.0.4 contain a stored cross-site scripting (XSS) vulnerability. An authenticated user with low privileges can inject malicious scripts that execute in the browsers of other site visitors, including administrators. The vulnerability affects the page builder's block rendering and persists across page loads. Site owners should update immediately to prevent account compromise and data theft.
What an attacker can do
03Attacker Capabilities
Inject malicious scripts that run in other users' browsers, potentially stealing credentials or session tokens.
Potential impact on your site
04Site Impact
Authenticated attackers can compromise admin accounts and steal sensitive data through stored XSS in page builder blocks.
Conditions required to exploit
05Prerequisites
Attacker needs a low-privilege WordPress account (e.g., contributor or editor role) and network access to the site.
Key dates
06Disclosure timeline
May 2, 2026
CVE published
May 4, 2026
Record updated
