CVE-2021-47856: Easy Cart Shopping Cart XSS Vulnerability

CVE-2021-47856 Overview

Easy Cart Shopping Cart 2021 contains a non-persistent (reflected) cross-site scripting (XSS) vulnerability in the search module's keyword parameter. Remote attackers can inject malicious script code through the search input to compromise user sessions and manipulate application content. This vulnerability allows attackers to execute arbitrary JavaScript in the context of an authenticated user's browser session.

Critical Impact

Attackers can steal session cookies, redirect users to malicious sites, deface the shopping cart interface, and perform actions on behalf of authenticated users including potential access to payment information.

Affected Products

• Easy Cart Shopping Cart 2021

Discovery Timeline

• 2026-02-01 - CVE CVE-2021-47856 published to NVD
• 2026-02-03 - Last updated in NVD database

Technical Details for CVE-2021-47856

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting (XSS). The flaw exists in the search functionality of Easy Cart Shopping Cart where user-supplied input through the keyword parameter is not properly sanitized before being reflected back in the application's response.

When a user performs a search query, the application echoes the search term back to the page without proper encoding or escaping. This allows an attacker to craft a malicious URL containing JavaScript code that will be executed when a victim clicks the link. Since this is a non-persistent (reflected) XSS vulnerability, the malicious payload is not stored on the server but is instead delivered through a crafted URL.

The attack requires user interaction—specifically, a victim must be convinced to click a malicious link. Once clicked, the injected script executes with the privileges of the authenticated user, potentially compromising their session.

Root Cause

The root cause of this vulnerability is insufficient input validation and output encoding in the search module. The keyword parameter accepts user input that is directly rendered in the HTML response without proper sanitization. The application fails to implement adequate output encoding mechanisms such as HTML entity encoding, which would neutralize potentially dangerous characters like <, >, ", and ' that are essential for JavaScript injection.

Attack Vector

This vulnerability is exploitable over the network without requiring prior authentication. An attacker can craft a malicious URL containing JavaScript code in the keyword parameter and distribute it through phishing emails, social media, or compromised websites. When a user clicks the malicious link while authenticated to the Easy Cart application, the injected script executes in their browser context.

A typical attack scenario involves the attacker constructing a URL with a payload in the search keyword parameter. The malicious script could perform actions such as stealing session cookies, capturing keystrokes, or redirecting users to phishing pages. The technical details and proof-of-concept information can be found in the Vulnerability Lab #2298 advisory.

Detection Methods for CVE-2021-47856

Indicators of Compromise

• Unusual search queries in web server logs containing HTML tags or JavaScript syntax such as <script>, javascript:, onerror=, or onload=
• User reports of unexpected browser behavior or pop-ups when using the search functionality
• Session hijacking attempts following search operations with encoded URL parameters

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block requests containing common XSS patterns in the keyword parameter
• Configure IDS/IPS signatures to alert on reflected XSS attack patterns targeting search functionality
• Review web server access logs for suspicious search queries containing encoded or plain-text script tags

Monitoring Recommendations

• Enable detailed logging of all search queries and monitor for anomalous patterns
• Set up alerts for requests containing potential XSS payload signatures
• Monitor for unusual session activity that may indicate successful exploitation

How to Mitigate CVE-2021-47856

Immediate Actions Required

• Implement input validation to restrict the keyword parameter to alphanumeric characters and expected special characters only
• Apply output encoding (HTML entity encoding) to all user-supplied data before rendering it in HTML responses
• Deploy a Web Application Firewall with XSS protection rules enabled to provide an additional layer of defense

Patch Information

No official vendor patch information is currently available. Organizations should consult the Net Art Media Overview page for any security updates or contact the vendor directly. For detailed technical information, refer to the VulnCheck Advisory on XSS.

Workarounds

• Implement Content Security Policy (CSP) headers to restrict script execution sources and mitigate XSS impact
• Use HTTP-only and Secure flags on session cookies to prevent theft via JavaScript
• Deploy a reverse proxy or WAF with XSS filtering capabilities in front of the application
• Consider temporarily disabling the search functionality if the risk is unacceptable until a patch is available

# Apache .htaccess CSP header configuration example
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'"

# Nginx CSP header configuration example
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'";