CVE-2026-2480: WP Shortcodes Ultimate Plugin XSS Flaw

CVE-2026-2480 Overview

The WP Shortcodes Plugin — Shortcodes Ultimate plugin for WordPress contains a Stored Cross-Site Scripting (XSS) vulnerability in the max_width attribute of the su_box shortcode. This security flaw exists in all versions up to, and including, 7.4.10 due to insufficient input sanitization and output escaping on user-supplied attributes. Authenticated attackers with contributor-level access and above can inject arbitrary web scripts into pages that execute whenever a user accesses the compromised page.

Critical Impact

Attackers with contributor-level WordPress access can inject persistent malicious scripts that execute in the browsers of all users who view affected pages, potentially leading to session hijacking, credential theft, and further site compromise.

Affected Products

• WP Shortcodes Plugin — Shortcodes Ultimate versions up to and including 7.4.10
• WordPress sites using vulnerable versions of the Shortcodes Ultimate plugin

Discovery Timeline

• 2026-03-31 - CVE-2026-2480 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2026-2480

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability exists within the su_box shortcode handler in the Shortcodes Ultimate plugin. The flaw stems from inadequate input sanitization and insufficient output escaping when processing the max_width attribute provided by users. When a contributor or higher-privileged user creates content using the su_box shortcode with a maliciously crafted max_width value, the unsanitized input is stored in the WordPress database and subsequently rendered without proper escaping when the page is viewed.

The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), a common weakness pattern for XSS vulnerabilities. The stored nature of this XSS makes it particularly dangerous as the malicious payload persists in the database and executes for every visitor who accesses the affected page.

Root Cause

The root cause of this vulnerability lies in the box.php shortcode handler file, specifically around lines 107 and 113 where the max_width attribute is processed. The plugin fails to properly sanitize user input before storing it and does not apply adequate output escaping when rendering the shortcode content. This allows specially crafted attribute values containing JavaScript code to be executed in the context of the victim's browser session.

The vulnerability exists because:

• Input validation does not reject or sanitize script content in the max_width parameter
• Output escaping functions are not applied when the attribute value is rendered into the HTML output
• The attribute is used in a context where script execution is possible

Attack Vector

The attack is network-based and requires an authenticated user with at least contributor-level privileges on the WordPress site. The attacker crafts a post or page containing the su_box shortcode with a malicious max_width attribute value designed to inject JavaScript code. Once the content is published or saved as a draft that others can preview, any user viewing the page will have the malicious script execute in their browser.

This attack vector enables:

• Session cookie theft leading to account takeover
• Keylogging of sensitive user input
• Defacement of website content
• Redirection to malicious external sites
• Privilege escalation if an administrator views the injected content

Detection Methods for CVE-2026-2480

Indicators of Compromise

• Unusual JavaScript code present in WordPress post content containing su_box shortcodes
• Unexpected max_width attribute values containing script tags, event handlers, or JavaScript URIs
• Browser console errors indicating blocked or executed inline scripts on pages using Shortcodes Ultimate
• Reports of suspicious redirects or popups when viewing pages with box shortcodes

Detection Strategies

• Review WordPress database for su_box shortcode instances with suspicious max_width attribute values containing characters like <, >, ", ', or javascript:
• Implement Content Security Policy (CSP) headers to detect and block unauthorized inline script execution
• Monitor web application firewall (WAF) logs for XSS payload patterns in POST requests to the WordPress editor
• Audit contributor and author-level user activity for suspicious content creation patterns

Monitoring Recommendations

• Enable WordPress audit logging to track content modifications by contributor-level users
• Configure real-time alerting for shortcode attribute values matching XSS patterns
• Deploy browser-based XSS detection tools during security testing of WordPress pages
• Regularly scan WordPress content database for known XSS payload signatures

How to Mitigate CVE-2026-2480

Immediate Actions Required

• Update the Shortcodes Ultimate plugin to the latest patched version immediately
• Audit existing content for potentially malicious su_box shortcode instances with suspicious max_width values
• Review and restrict contributor-level user accounts to trusted individuals only
• Implement a Web Application Firewall (WAF) rule to filter XSS payloads in shortcode attributes

Patch Information

The vulnerability has been addressed in the WordPress Shortcodes Ultimate changeset. Site administrators should update to the latest version of the plugin through the WordPress admin dashboard or by downloading directly from the WordPress plugin repository. Additional details about the vulnerability can be found in the Wordfence Vulnerability Report.

Workarounds

• Temporarily disable the Shortcodes Ultimate plugin until the update can be applied
• Remove contributor-level access from untrusted users until the patch is deployed
• Use WordPress hooks to add custom sanitization for the su_box shortcode max_width attribute
• Implement strict Content Security Policy headers to mitigate the impact of any successful XSS injection

# Configuration example - Add to WordPress .htaccess or server config
# Implement Content Security Policy headers to mitigate XSS impact
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"