CVE-2026-30565: Sales And Inventory System XSS Flaw

CVE-2026-30565 Overview

A Reflected Cross-Site Scripting (XSS) vulnerability exists in SourceCodester Sales and Inventory System 1.0. The vulnerability is located in the view_supplier.php file via the limit parameter. The application fails to sanitize the input, allowing remote attackers to inject arbitrary web script or HTML via a crafted URL.

Critical Impact

Attackers can execute arbitrary JavaScript in the context of authenticated users' browsers, potentially leading to session hijacking, credential theft, or unauthorized actions within the Sales and Inventory System.

Affected Products

• SourceCodester Sales and Inventory System 1.0
• ahsanriaz26gmailcom sales_and_inventory_system

Discovery Timeline

• 2026-03-30 - CVE CVE-2026-30565 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2026-30565

Vulnerability Analysis

This Reflected Cross-Site Scripting vulnerability occurs when user-supplied input through the limit parameter in view_supplier.php is echoed back to the browser without proper sanitization or encoding. When a victim clicks a malicious link containing the crafted payload, the injected script executes within their browser session under the context of the vulnerable application.

The vulnerability requires user interaction—specifically, the victim must be tricked into clicking a malicious URL. Upon successful exploitation, attackers can steal session cookies, capture user credentials, modify page content to display fraudulent information, or perform actions on behalf of the authenticated user within the Sales and Inventory System.

Root Cause

The root cause of this vulnerability is inadequate input validation and output encoding in the view_supplier.php file. The limit parameter value is directly reflected in the HTTP response without being properly sanitized against HTML/JavaScript special characters. This failure to implement proper output encoding (such as HTML entity encoding) allows attacker-controlled script content to be interpreted as executable code by the victim's browser.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker crafts a malicious URL containing JavaScript payload in the limit parameter and distributes it via phishing emails, malicious websites, or social engineering tactics. When an authenticated user clicks the link, the malicious script executes in their browser session.

The vulnerability allows attackers to target users of the Sales and Inventory System by crafting URLs that contain malicious payloads. When victims navigate to these URLs, the unsanitized input is reflected in the page response and executed as JavaScript code. A proof of concept demonstrating this vulnerability is available at the GitHub XSS Proof of Concept.

Detection Methods for CVE-2026-30565

Indicators of Compromise

• Suspicious HTTP requests to view_supplier.php containing JavaScript tags or encoded script content in the limit parameter
• Unexpected URL patterns with HTML entities or script injection attempts in query strings
• User reports of unexpected browser behavior or phishing attempts related to the Sales and Inventory System
• Web application firewall logs showing blocked XSS patterns targeting the limit parameter

Detection Strategies

• Deploy web application firewall (WAF) rules to detect and block common XSS patterns in query parameters
• Implement Content Security Policy (CSP) headers to prevent inline script execution
• Monitor web server access logs for requests containing suspicious characters such as <script>, javascript:, or encoded equivalents in the limit parameter
• Use browser-based XSS auditors and security headers to provide additional defense layers

Monitoring Recommendations

• Enable detailed logging for the view_supplier.php endpoint and review for anomalous parameter values
• Configure alerts for requests containing potential XSS payloads in URL parameters
• Implement real-time monitoring of web traffic for injection attack patterns
• Review authentication logs for sessions that may have been compromised following suspicious requests

How to Mitigate CVE-2026-30565

Immediate Actions Required

• Implement input validation on the limit parameter to accept only expected numeric values
• Apply output encoding (HTML entity encoding) when reflecting user input back to the browser
• Deploy Content Security Policy (CSP) headers to mitigate the impact of any successful XSS attacks
• Consider restricting access to the Sales and Inventory System until a patch is applied

Patch Information

No official vendor patch is currently available for this vulnerability. Organizations using SourceCodester Sales and Inventory System 1.0 should implement the workarounds described below and monitor for vendor updates. The vulnerability details and proof of concept are documented in the GitHub XSS Proof of Concept.

Workarounds

• Manually patch the view_supplier.php file to sanitize the limit parameter using htmlspecialchars() or equivalent encoding functions
• Implement a web application firewall (WAF) rule to filter malicious input on the limit parameter
• Restrict access to the application to trusted internal networks only until a proper fix is available
• Educate users about the risks of clicking unknown links related to the inventory system

# Example: Add Content Security Policy header in Apache configuration
# Add to .htaccess or httpd.conf
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'"

# Example: PHP input sanitization for the limit parameter
# Add to view_supplier.php before using $limit variable
# $limit = isset($_GET['limit']) ? intval($_GET['limit']) : 10;
# OR for output encoding:
# $limit = htmlspecialchars($_GET['limit'], ENT_QUOTES, 'UTF-8');