CVE-2026-4658 json
Gutenberg Essential Blocks <= 6.0.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via Block Attributes
published 2026-05-02 6 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-26733
- cvss
- 6.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 36%
- public exploits
- 0
- none known
Summary
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.
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 6 mo ago
Exploit prediction
0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.4 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N |
Affected products
- wpdevteam Gutenberg Essential Blocks – Page Builder for Gutenberg Blocks & Patterns
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
- Technology feeds
References
- wordfence.com /threat-intel/vulnerabilities/id/3e7eed9d-2d44-4951-b66b-7d8995ca617d?source=cve
- plugins.trac.wordpress.org /browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L118
- plugins.trac.wordpress.org /browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L118
- plugins.trac.wordpress.org /browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L120
- plugins.trac.wordpress.org /browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L120
- plugins.trac.wordpress.org /browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L65
- plugins.trac.wordpress.org /browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L65
- plugins.trac.wordpress.org /browser/essential-blocks/trunk/includes/Blocks/AddToCart.php#L66
- plugins.trac.wordpress.org /browser/essential-blocks/tags/6.0.4/includes/Blocks/AddToCart.php#L66
- plugins.trac.wordpress.org /changeset?sfp_email=&sfph_mail=&reponame=&new=3516287%40essential-blocks%2Ftags%2F6.1.0%2Fincludes%2FBlocks%2
Sources
- CVE List CVE-2026-4658
- NVD CVE-2026-4658
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.