CVE-2026-0552: WordPress Simple Shopping Cart XSS Flaw

CVE-2026-0552 Overview

The Simple Shopping Cart plugin for WordPress is vulnerable to Stored Cross-Site Scripting (XSS) via the plugin's wpsc_display_product shortcode in all versions up to, and including, 5.2.4. The vulnerability exists due to insufficient input sanitization and output escaping on user-supplied attributes. This allows authenticated attackers with contributor-level access and above to inject arbitrary web scripts into pages that will execute whenever a user accesses the affected page.

Critical Impact

Authenticated attackers can inject persistent malicious scripts that execute in victim browsers, potentially leading to session hijacking, credential theft, and unauthorized actions performed on behalf of legitimate users.

Affected Products

• Simple Shopping Cart plugin for WordPress versions up to and including 5.2.4
• WordPress installations using the vulnerable wpsc_display_product shortcode
• Sites where contributors or higher-level users can create/edit content

Discovery Timeline

• 2026-04-04 - CVE-2026-0552 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-0552

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability affects the Simple Shopping Cart plugin's wpsc_display_product shortcode functionality. The core issue stems from improper handling of user-supplied attributes within the shortcode implementation. When authenticated users with at least contributor-level privileges create or modify content containing the vulnerable shortcode, they can embed malicious JavaScript payloads that persist in the database.

The stored nature of this XSS vulnerability makes it particularly dangerous as the malicious payload executes automatically whenever any user—including administrators—views the affected page. This creates opportunities for privilege escalation, where a lower-privileged attacker could potentially capture administrator session tokens or perform administrative actions through the injected script.

The vulnerability requires no user interaction beyond viewing the compromised page, making it an effective vector for widespread attacks on WordPress site visitors and administrators alike.

Root Cause

The root cause of this vulnerability is insufficient input sanitization and output escaping on user-supplied attributes within the wpsc_display_product shortcode handler. The plugin fails to properly validate and sanitize attribute values before storing them in the database and subsequently fails to escape these values when rendering them in the HTML output. This lack of defense-in-depth allows specially crafted attribute values containing JavaScript code to be stored and later executed in the browser context of users viewing the affected pages.

Attack Vector

The attack is network-accessible and requires an authenticated attacker with at least contributor-level access to the WordPress installation. The attacker crafts a malicious shortcode using wpsc_display_product with specially formatted attributes containing JavaScript payloads. Once the content is saved and published (or submitted for review), any user viewing the page will have the malicious script execute in their browser session.

The attack flow involves:

1. Attacker authenticates to WordPress with contributor or higher privileges
2. Attacker creates or edits a post/page containing the wpsc_display_product shortcode with malicious attribute values
3. The unsanitized payload is stored in the WordPress database
4. When victims view the affected page, the malicious JavaScript executes in their browser
5. The script can steal session cookies, perform actions as the victim, or redirect users to malicious sites

Due to the authenticated requirement and contributor-level access needed, exploitation requires either compromised credentials or a malicious insider with content creation privileges.

Detection Methods for CVE-2026-0552

Indicators of Compromise

• Unusual JavaScript code embedded within wpsc_display_product shortcode attributes in WordPress posts or pages
• Unexpected outbound requests to external domains from user browsers when viewing shopping cart pages
• Reports from users experiencing redirects or unexpected behavior on product pages
• Audit logs showing contributor-level users creating content with encoded or obfuscated shortcode attributes

Detection Strategies

• Monitor WordPress database for posts containing wpsc_display_product shortcodes with suspicious attribute patterns such as <script>, javascript:, onerror=, or event handlers
• Implement Web Application Firewall (WAF) rules to detect and block XSS payloads in shortcode attributes
• Review content created by contributor-level users for anomalous shortcode usage patterns
• Deploy browser-based content security policies to limit script execution sources

Monitoring Recommendations

• Enable WordPress audit logging to track content modifications by contributor-level users
• Configure SentinelOne Singularity to monitor for suspicious JavaScript execution patterns on WordPress servers
• Implement Content Security Policy (CSP) headers to detect and report inline script violations
• Regularly scan stored content for XSS patterns using automated security scanning tools

How to Mitigate CVE-2026-0552

Immediate Actions Required

• Update the Simple Shopping Cart plugin to a version newer than 5.2.4 immediately
• Review all existing posts and pages containing wpsc_display_product shortcodes for malicious content
• Temporarily restrict contributor-level access if immediate patching is not possible
• Implement a Web Application Firewall with XSS protection rules as an additional layer of defense

Patch Information

A security patch addressing this vulnerability is available. The fix can be verified through the WordPress Plugin Changeset which implements proper input sanitization and output escaping for shortcode attributes. Site administrators should update to the patched version through the WordPress admin dashboard or by manually downloading the latest version from the WordPress plugin repository.

For additional technical details about this vulnerability, refer to the Wordfence Vulnerability Report.

Workarounds

• Temporarily disable the Simple Shopping Cart plugin until the patch can be applied
• Remove contributor-level access from untrusted users until the vulnerability is remediated
• Implement server-side output encoding for all shortcode-rendered content
• Deploy Content Security Policy headers to prevent inline script execution as a defense-in-depth measure

# Example Content Security Policy header configuration for Apache
# Add to .htaccess or virtual host configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';"