Executive Summary

CVE-2026-11518 is a Stored Cross-Site Scripting (XSS) vulnerability in SourceCodester Inventory System 1.0, specifically in the Staff Registration module (register.php). The vulnerability arises because the fullname and username input fields do not properly sanitize or encode user input before storing it in the database.

An attacker can inject malicious JavaScript code into these fields without authentication. When an administrator later views the User Management page (users.php), the malicious scripts are executed in the admin's browser, potentially compromising the admin's session and allowing unauthorized actions.

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Compliance Impact

The vulnerability allows an attacker to execute malicious scripts in the administrator's browser session, potentially leading to session hijacking and unauthorized admin-level actions.

Such unauthorized access and manipulation of sensitive data could lead to violations of data protection regulations like GDPR and HIPAA, which require safeguarding personal and sensitive information against unauthorized access and breaches.

Failure to properly sanitize and encode user inputs, as seen in this vulnerability, undermines the security controls necessary to maintain compliance with these standards.

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Impact Analysis

This vulnerability can have serious impacts including the hijacking of the administrator's session, execution of malicious scripts within the admin panel, and unauthorized manipulation of inventory data.

• Stealing the admin's session cookie to gain unauthorized access.
• Redirecting the admin to phishing pages.
• Performing admin-level actions silently without the administrator's knowledge.

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Detection Guidance

This vulnerability can be detected by testing the Staff Registration module (register.php) for improper input sanitization in the fullname and username fields. Specifically, you can attempt to inject typical XSS payloads such as <script>alert(1)</script> into these fields and then check if the payload executes when viewing the User Management page (users.php).

To detect it on your system, you can use web application testing tools or manual curl commands to submit payloads and observe the response.

• Example curl command to test injection: curl -X POST -d "fullname=<script>alert(1)</script>&username=testuser" http://targetsite/register.php
• After submitting, visit the User Management page (users.php) as an admin to see if the script executes.

Additionally, automated scanners that detect stored XSS vulnerabilities can be used to identify this issue.

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Mitigation Strategies

Immediate mitigation steps include sanitizing and encoding all user inputs and outputs related to the fullname and username fields.

• Apply output encoding using htmlspecialchars() with ENT_QUOTES in users.php before rendering user-supplied data in HTML.
• Validate and sanitize all inputs on the server side in register.php to prevent malicious scripts from being stored.
• Implement a Content Security Policy (CSP) header to reduce the impact of any potential XSS payload execution.

These steps will help prevent the injection and execution of malicious scripts, protecting admin sessions and data integrity.

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