CVE-2026-4658
CWE-79Published: May 2, 2026· Updated: May 5, 2026
Official 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.
Technical Analysis
CVE-2026-4658 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.
From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (10)
Quick Facts
Related CVEs (CWE-79)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-4658 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts