PT-2026-36565 · WordPress · Essential Blocks

Darkestmode + 1 · Published 2026-05-02 · Updated 2026-05-02 · CVE-2026-4658

Positive Technologies (AI Summary)

CVSS v3.1

6.4

Medium

Base vector

AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Name of the Vulnerable Software and Affected Versions Essential Blocks – Page Builder Gutenberg Blocks, Patterns & Templates versions prior to 6.0.5

Description Stored Cross-Site Scripting is possible via the className, classHook, and blockId attributes in the 'Add to Cart' block ('essential-blocks/add-to-cart'). The issue occurs in the render callback() function due to insufficient output escaping when these attributes are placed into class and data-id HTML attributes using sprintf() and implode() without esc attr() escaping. Authenticated attackers with Contributor-level access or higher can inject arbitrary web scripts into pages, which execute when a user visits the affected page.

Recommendations Update to a version newer than 6.0.4.

Fix

XSS

Weakness Enumeration

CWE-79

Related Identifiers

CVE-2026-4658

Affected Products

Essential Blocks

References · 14

• https://nvd.nist.gov/vuln/detail/CVE-2026-4658 · Security Note
• https://t.me/CVEtracker/52482 · Telegram Post
• https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L65 · Note
• https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L120 · Note
• https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L65 · Note
• https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L66 · Note
• https://t.me/cveNotify/161840 · Telegram Post
• https://wordfence.com/threat-intel/vulnerabilities/id/3e7eed9d-2d44-4951-b66b-7d8995ca617d?source=cve · Note
• https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L120 · Note
• https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L118 · Note
• https://plugins.trac.wordpress.org/browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L118 · Note
• https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&new=3516287%40essential-blocks%2Ftags%2F6.1.0%2Fincludes%2FBlocks%2FAddToCart.php&old=3178777%40essential-blocks%2Ftrunk%2Fincludes%2FBlocks%2FAddToCart.php · Note
• https://plugins.trac.wordpress.org/browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L66 · Note
• https://twitter.com/VulmonFeeds/status/2050468903982084325 · Twitter Post