CVE-2026-90694: Inventory Management System XSS Vulnerability

CVE-2026-90694 Overview

CVE-2026-90694 is a reflected cross-site scripting (XSS) vulnerability in SourceCodester Inventory Management System 1.0. The flaw resides in the Customer Management Module, specifically in the /api/customers_handler.php endpoint. Attackers can inject arbitrary JavaScript through the Customer_Name parameter, which the application renders without sufficient output encoding.

The exploit has been publicly disclosed and can be executed remotely over the network. Successful exploitation requires an authenticated low-privileged user and some form of user interaction, such as visiting a crafted link or record view. The issue is tracked as [CWE-79] (Improper Neutralization of Input During Web Page Generation).

Critical Impact
Attackers can execute arbitrary JavaScript in the browser context of authenticated users, enabling session-context actions, UI defacement, and credential harvesting via crafted Customer_Name values.

Affected Products

SourceCodester Inventory Management System 1.0
Component: Customer Management Module
Endpoint: /api/customers_handler.php

Discovery Timeline

2026-09-14 - CVE-2026-90694 published to the National Vulnerability Database
2026-09-14 - Last updated in NVD database

Technical Details for CVE-2026-90694

Vulnerability Analysis

The vulnerability exists in the customer handling logic exposed by /api/customers_handler.php. The application accepts a Customer_Name argument and later renders that value inside HTML output without proper encoding or sanitization. An attacker who submits HTML or JavaScript payloads in this field can cause the browser to execute the payload when the affected page is viewed.

Because the injection occurs within the Customer Management Module, common exploitation scenarios include stored or reflected script execution in the context of an administrator or operator reviewing customer records. The attacker can then perform any action the victim is authorized to perform inside the application session.

Root Cause

The root cause is missing output encoding on user-supplied data flowing from the Customer_Name request argument into an HTML rendering context. The handler does not apply HTML entity encoding or a strict input allowlist before echoing the value back to the DOM, which matches the [CWE-79] pattern.

Attack Vector

Exploitation is network-based and requires user interaction. An authenticated low-privileged actor submits a crafted Customer_Name value through the customers handler. When another user opens the affected customer view, the injected script runs in that user's browser session against the vulnerable application origin.

No verified proof-of-concept code is published in the enriched data. Refer to the GitHub Gist Code Snippet and VulDB CVE-2026-90694 entry for the disclosed technical details.

Detection Methods for CVE-2026-90694

Indicators of Compromise

HTTP requests to /api/customers_handler.php containing angle brackets, <script>, javascript:, or common event handlers such as onerror= and onload= in the Customer_Name parameter.
Customer records whose stored Customer_Name values contain HTML tags or encoded script fragments.
Unexpected outbound requests from operator browsers to attacker-controlled domains shortly after opening the customer list or details view.

Detection Strategies

Inspect web server and application logs for POST or GET requests to customers_handler.php with payloads matching XSS signatures.
Deploy a Web Application Firewall (WAF) rule that flags HTML and JavaScript metacharacters submitted to the Customer Management Module.
Perform database review across the customers table for HTML markup persisted in name fields.

Monitoring Recommendations

Enable Content Security Policy (CSP) violation reporting to capture script execution attempts blocked by the browser.
Alert on anomalous session activity from operator accounts immediately after they access injected customer records.
Correlate authentication events with subsequent administrative actions to detect session-riding behavior driven by XSS.

How to Mitigate CVE-2026-90694

Immediate Actions Required

Restrict access to the Inventory Management System to trusted networks or place it behind a VPN until a vendor patch is applied.
Audit and sanitize existing customer records for stored HTML or JavaScript in Customer_Name fields.
Rotate credentials for any privileged account that may have viewed attacker-controlled customer records.

Patch Information

No official vendor patch is listed in the enriched data for SourceCodester Inventory Management System 1.0. Monitor the SourceCodester Resource Index and the VulDB Vulnerability #403227 record for updated remediation guidance and any code revisions.

Workarounds

Add server-side output encoding by wrapping Customer_Name rendering with htmlspecialchars($value, ENT_QUOTES, 'UTF-8') before it reaches the response body.
Enforce an input allowlist on the Customer_Name parameter that rejects <, >, and quote characters at the handler layer.
Deploy a strict Content Security Policy that disables inline script execution and restricts script sources to the application origin.
Apply WAF rules blocking common XSS payload patterns targeting /api/customers_handler.php.

bash

# Example Apache ModSecurity rule to block script tags in Customer_Name
SecRule ARGS:Customer_Name "@rx (?i)(<script|javascript:|onerror=|onload=)" \
    "id:1029069,phase:2,deny,status:403,log,msg:'Blocked XSS attempt on customers_handler.php'"