CVE-2026-4658Network attack vector

Stored XSS via unescaped Add to Cart attributes

Published May 2, 2026 · Updated May 2, 2026

Stored XSS in WPDeveloper Essential Blocks for Gutenberg 6.0.4 and earlier allows remote authenticated users to inject scripts into pages. The Add to Cart render_callback() inserts className, classHook, and blockId values into class and data-id attributes through raw sprintf() and implode() output without esc_attr(). Contributor-level access is sufficient, and the injected JavaScript executes in a visitor's browser when the crafted page is viewed.

CVSS severity6.4
Medium
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in WPDeveloper Essential Blocks for Gutenberg 6.0.4 and earlier allows remote authenticated users to inject scripts into pages. The Add to Cart render_callback() inserts className, classHook, and blockId values into class and data-id attributes through raw sprintf() and implode() output without esc_attr(). Contributor-level access is sufficient, and the injected JavaScript executes in a visitor's browser when the crafted page is viewed.

The record

CVE
CVE-2026-4658
Published
May 2, 2026
Updated
May 2, 2026
Vendor
ReviewX Team
Product
Essential Blocks for Gutenberg
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 2, 2026CVE publishedPublication date reported by the CVE source.
  2. May 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=6.0.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

ReviewX Team · Essential Blocks for Gutenbergversion=0 <=6.0.4

Published CVSS scores

6.4WordfenceCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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