CVE-2026-30569: Inventory System Reflected XSS Vulnerability

CVE-2026-30569 Overview

A Reflected Cross-Site Scripting (XSS) vulnerability exists in SourceCodester Sales and Inventory System 1.0. The vulnerability is located in the view_stock_availability.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 victim browsers, potentially stealing session cookies, capturing credentials, or performing actions on behalf of authenticated users within the inventory management system.

Affected Products

• SourceCodester Sales and Inventory System 1.0
• ahsanriaz26gmailcom inventory_system 1.0

Discovery Timeline

• 2026-03-27 - CVE CVE-2026-30569 published to NVD
• 2026-03-31 - Last updated in NVD database

Technical Details for CVE-2026-30569

Vulnerability Analysis

This reflected XSS vulnerability exists due to improper input validation in the stock availability viewing functionality. The view_stock_availability.php endpoint accepts a limit parameter that is directly reflected in the response without adequate sanitization or encoding. This allows attackers to craft malicious URLs containing JavaScript payloads that execute when victims click the link.

The vulnerability requires user interaction—a victim must click a specially crafted link containing the malicious payload. When executed, the injected script runs within the context of the authenticated user's session, providing attackers with access to sensitive information and the ability to perform unauthorized actions within the inventory management application.

Root Cause

The root cause is a classic input validation failure (CWE-79: Improper Neutralization of Input During Web Page Generation). The limit parameter value is incorporated into the HTML response without proper output encoding or sanitization. The application lacks appropriate security controls such as:

• Input validation to restrict the limit parameter to expected numeric values
• Output encoding to neutralize potentially dangerous characters
• Content Security Policy (CSP) headers that could mitigate script execution

Attack Vector

The attack is network-based and requires no authentication on the part of the attacker. The exploitation path involves:

1. An attacker crafts a malicious URL targeting view_stock_availability.php with a JavaScript payload in the limit parameter
2. The attacker distributes the malicious link via phishing emails, social media, or other channels
3. When an authenticated user clicks the link, the malicious script executes in their browser
4. The script can then steal session tokens, capture keystrokes, redirect users, or perform actions as the victim

A proof of concept demonstrating this vulnerability is available at the GitHub XSS Proof of Concept repository, which details the specific payload structure used to trigger the vulnerability.

Detection Methods for CVE-2026-30569

Indicators of Compromise

• Unusual HTTP requests to view_stock_availability.php containing script tags or JavaScript event handlers in the limit parameter
• Web server logs showing encoded JavaScript payloads such as %3Cscript%3E or javascript: in URL parameters
• Reports from users of unexpected browser behavior or pop-ups when accessing the inventory system
• Session anomalies where user accounts perform actions from unusual IP addresses or at unexpected times

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block XSS payloads in the limit parameter
• Configure server-side logging to capture full request URLs and monitor for suspicious patterns
• Deploy browser-based security tools that can detect and report attempted XSS attacks
• Utilize SIEM correlation rules to identify clusters of requests containing common XSS payload signatures

Monitoring Recommendations

• Enable detailed access logging for the view_stock_availability.php endpoint
• Set up alerts for requests containing <script>, onerror=, onclick=, and other common XSS trigger patterns
• Monitor for unusual authentication patterns that may indicate compromised sessions
• Implement real-time log analysis to detect exploitation attempts as they occur

How to Mitigate CVE-2026-30569

Immediate Actions Required

• Restrict access to the vulnerable view_stock_availability.php endpoint until a patch is applied
• Implement a Web Application Firewall (WAF) rule to block requests with suspicious characters in the limit parameter
• Review server logs for evidence of exploitation attempts
• Consider taking the application offline if it processes sensitive business data

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. For technical details about the vulnerability, refer to the GitHub XSS Proof of Concept.

Workarounds

• Manually modify view_stock_availability.php to validate that the limit parameter contains only numeric values
• Implement server-side output encoding using htmlspecialchars() or equivalent functions for all user-supplied input
• Add Content Security Policy (CSP) headers to restrict inline script execution
• Deploy a reverse proxy or WAF to filter malicious requests before they reach the application

# Example Apache configuration to add CSP headers
<IfModule mod_headers.c>
    Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'"
    Header set X-XSS-Protection "1; mode=block"
    Header set X-Content-Type-Options "nosniff"
</IfModule>