CVE-2026-30567: Inventory System Reflected XSS Vulnerability

CVE-2026-30567 Overview

CVE-2026-30567 is a reflected Cross-Site Scripting (XSS) vulnerability in SourceCodester Sales and Inventory System 1.0. The flaw resides in the view_product.php file and is triggered through the limit GET parameter. The application fails to sanitize user-supplied input before reflecting it back into the HTTP response. Remote attackers can craft a malicious URL that injects arbitrary HTML or JavaScript into the rendered page. When a victim clicks the link, the injected script executes in the browser under the application's origin. The issue is classified as [CWE-79] Improper Neutralization of Input During Web Page Generation.

Critical Impact

Attackers can hijack user sessions, steal authentication cookies, or perform actions as the victim within the inventory management application.

Affected Products

• SourceCodester Sales and Inventory System 1.0
• ahsanriaz26gmailcom inventory_system 1.0
• Deployments using the unpatched view_product.php endpoint

Discovery Timeline

• 2026-03-27 - CVE-2026-30567 published to NVD
• 2026-05-10 - Last updated in NVD database

Technical Details for CVE-2026-30567

Vulnerability Analysis

The vulnerability exists in the view_product.php script, which accepts a limit query parameter intended to control pagination. The application embeds this parameter directly into the HTML response without applying output encoding or input validation. An attacker who supplies JavaScript payloads through the limit parameter causes the browser to execute that code in the context of the application's domain. Because authentication is not required to reach the vulnerable endpoint, exploitation only depends on convincing a logged-in user to load a crafted URL. The scope change reflected in the CVSS vector indicates the injected script can affect resources beyond the vulnerable component, including session cookies and DOM elements of the parent application.

Root Cause

The root cause is missing input sanitization and missing output encoding on the limit parameter inside view_product.php. The script concatenates the parameter value into HTML output without using context-aware escaping functions such as htmlspecialchars(). PHP's default request handling does not encode untrusted input, so the burden falls on the developer to neutralize special characters like <, >, and ".

Attack Vector

Exploitation is network-based and requires user interaction. An attacker delivers a malicious URL pointing to view_product.php with a JavaScript payload appended to the limit parameter. Common delivery channels include phishing emails, malicious chat messages, and attacker-controlled web pages. When an authenticated user visits the URL, the payload executes and can exfiltrate session tokens, modify rendered content, or trigger CSRF actions against the inventory backend.

No verified exploit code is published in the NVD record. A proof of concept is referenced in the GitHub XSS Proof of Concept repository, which documents the parameter manipulation required to trigger the flaw.

Detection Methods for CVE-2026-30567

Indicators of Compromise

• HTTP GET requests to view_product.php containing URL-encoded <script>, onerror=, or javascript: tokens in the limit parameter
• Web server access logs showing unusually long or encoded values in the limit query string
• Browser console errors or anomalous outbound requests originating from authenticated inventory sessions

Detection Strategies

• Deploy a Web Application Firewall (WAF) rule that inspects the limit parameter for HTML and JavaScript metacharacters
• Review application access logs for repeated requests to view_product.php with non-numeric limit values
• Correlate user session activity with referrer headers pointing to external or suspicious domains

Monitoring Recommendations

• Enable verbose HTTP request logging on the application server and forward logs to a centralized analytics platform
• Alert on outbound requests from user browsers to unknown domains immediately after visiting view_product.php
• Monitor for repeated 200-OK responses to URLs containing encoded %3Cscript%3E patterns

How to Mitigate CVE-2026-30567

Immediate Actions Required

• Restrict access to the Sales and Inventory System to trusted networks until a patch is applied
• Apply server-side input validation to enforce numeric-only values on the limit parameter
• Educate users about the risk of clicking unsolicited links pointing to internal applications

Patch Information

No vendor advisory or official patch is referenced in the NVD record for CVE-2026-30567. Administrators should monitor the SourceCodester project channels for an updated release. Until a fix is published, custom code modifications to view_product.php are required to neutralize the limit parameter through functions such as htmlspecialchars($_GET['limit'], ENT_QUOTES, 'UTF-8') or strict type casting with intval().

Workarounds

• Cast the limit parameter to an integer with intval() before using it in queries or output
• Deploy a WAF signature that blocks HTML tags and JavaScript event handlers in query parameters targeting view_product.php
• Enforce a strict Content Security Policy (CSP) that disallows inline scripts on the inventory application

# Example Nginx rule to block script payloads in the limit parameter
location /view_product.php {
    if ($arg_limit ~* "(<|%3C)\s*script|javascript:|onerror=|onload=") {
        return 403;
    }
}