CVE-2026-13203

Live Composer <= 2.1.19 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'custom_id' Shortcode Attribute

2026-08-31 15:53
Osvaldo Noe Gonzalez Del Rio (Os)

Strategic Overview

Status
Patched in 2.1.20
Affected Plugin
Live Composer – Free WordPress Website Builder
Affected Version
<= 2.1.19
CVSS
6.4Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-13203
View all Live Composer – Free WordPress Website Builder vulnerabilities

At a glance

CVE-2026-13203 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Live Composer WordPress plugin, affecting versions <= 2.1.19. It carries a CVSS score of 6.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Contributor level or above. The issue is fixed in version 2.1.20; sites on affected versions should update now. Disclosed August 2026, reported by Osvaldo Noe Gonzalez Del Rio (Os).

Vulnerability Overview

The Live Composer – Free WordPress Website Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'custom_id' shortcode attribute of the dslc_modules_section and dslc_modules_area shortcodes in versions up to, and including, 2.1.19. This is due to insufficient input sanitization and output escaping on the user-supplied attribute, which is concatenated into the HTML id="" attribute of the rendered <div> element in the dslc_modules_section_front() and dslc_modules_area_front() functions without esc_attr(). 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.

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')

Live Composer <= 2.1.19 carries this weakness at custom_id, and reaching it takes an account at Contributor 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 Live Composer the fix is 2.1.20: builds <= 2.1.19 are affected, anything from 2.1.20 onward is not.

Remediation

Update to version 2.1.20, or a newer patched version

How does WordSec protect against this?

An attacker needs Contributor 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: Live Composer 2.1.20 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-13203https://www.wordfence.com/threat-intel/vulnerabilities/id/9b9e0302-b981-4885-822f-063247bec4b2https://nvd.nist.gov/vuln/detail/CVE-2026-13203

Related records

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