{"id":"CVE-2026-4658","aliases":["EUVD-2026-26733","GHSA-5vvh-659m-gjm3"],"status":"published","title":"Gutenberg Essential Blocks \u003c= 6.0.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via Block Attributes","description":"The Essential Blocks – Page Builder Gutenberg Blocks, Patterns \u0026 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.","severity":{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00419,"percentile":0.36449,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-79"],"published":"2026-05-02T04:27:44Z","modified":"2026-06-17T10:56:59Z","products":[{"vendor":"wpdevteam","product":"gutenberg essential blocks – page builder for gutenberg blocks \u0026 patterns"}],"references":[{"url":"https://www.wordfence.com/threat-intel/vulnerabilities/id/3e7eed9d-2d44-4951-b66b-7d8995ca617d?source=cve"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L118"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L118"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L120"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L120"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L65"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L65"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L66"},{"url":"https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L66"},{"url":"https://plugins.trac.wordpress.org/changeset?sfp_email=\u0026sfph_mail=\u0026reponame=\u0026new=3516287%40essential-blocks%2Ftags%2F6.1.0%2Fincludes%2FBlocks%2FAddToCart.php\u0026old=3178777%40essential-blocks%2Ftrunk%2Fincludes%2FBlocks%2FAddToCart.php"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-4658"},{"url":"https://github.com/advisories/GHSA-5vvh-659m-gjm3"}],"sources":{"cve":[{"id":"CVE-2026-4658","title":"Gutenberg Essential Blocks \u003c= 6.0.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via Block Attributes","description":"The Essential Blocks – Page Builder Gutenberg Blocks, Patterns \u0026 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.","status":"published","published":"2026-05-02T04:27:44.707Z","modified":"2026-05-04T16:03:39.376Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:19:59.369956Z"}],"euvd":[{"id":"EUVD-2026-26733","description":"The Essential Blocks – Page Builder Gutenberg Blocks, Patterns \u0026 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.","status":"published","published":"2026-05-02T04:27:44Z","modified":"2026-05-04T16:03:39Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T19:05:17.945759Z"}],"ghsa":[{"id":"GHSA-5vvh-659m-gjm3","title":"The Essential Blocks – Page Builder Gutenberg Blocks, Patterns \u0026 Templates plugin for WordPress...","description":"The Essential Blocks – Page Builder Gutenberg Blocks, Patterns \u0026 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.","status":"published","published":"2026-05-02T06:30:23Z","modified":"2026-05-02T06:30:30Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T15:07:53.39389Z"}],"nvd":[{"id":"CVE-2026-4658","description":"The Essential Blocks – Page Builder Gutenberg Blocks, Patterns \u0026 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.","status":"published","published":"2026-05-02T05:16:00.767Z","modified":"2026-06-17T10:56:59.143Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-79"],"updated_at":"2026-11-02T14:12:17.022502Z"}]}}