CVE-2026-6378

Maxi Blocks <= 2.1.9 - Authenticated (Author+) Stored Cross-Site Scripting via Style Card REST API

2026-05-01 14:44
Athiwat Tiprasaharn (Jitlada)

Strategic Overview

Status
Patched in 2.1.10
Affected Plugin
MaxiBlocks Builder | 17,000+ Design Assets, Patterns, Icons & Starter Sites
Affected Version
<= 2.1.9
CVSS
6.4Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-6378
View all MaxiBlocks Builder | 17,000+ Design Assets, Patterns, Icons & Starter Sites vulnerabilities

At a glance

CVE-2026-6378 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the MaxiBlocks Builder WordPress plugin, affecting versions <= 2.1.9. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Author level or above. The issue is fixed in version 2.1.10; sites on affected versions should update now. Disclosed May 2026, reported by Athiwat Tiprasaharn (Jitlada).

Vulnerability Overview

The Maxi Blocks plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the `/wp-json/maxi-blocks/v1.0/style-card` REST API endpoint in all versions up to, and including, 2.1.9 due to insufficient input sanitization and output escaping of the `sc_styles` parameter. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts that execute on every page where the plugin's style card styles are loaded, including across the entire WordPress admin panel.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user.

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Reaching this weakness in MaxiBlocks Builder <= 2.1.9 takes an account at Author level or above. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For MaxiBlocks Builder the fix is 2.1.10: builds <= 2.1.9 are affected, anything from 2.1.10 onward is not.

Remediation

Update to version 2.1.10, or a newer patched version

How does WordSec protect against this?

An attacker needs Author access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: MaxiBlocks Builder 2.1.10 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-6378https://www.wordfence.com/threat-intel/vulnerabilities/id/22f05048-df38-4f26-82a3-53caac995283https://nvd.nist.gov/vuln/detail/CVE-2026-6378

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C