CVE-2026-90695: Inventory Management System XSS Vulnerability

CVE-2026-90695 Overview

CVE-2026-90695 is a reflected cross-site scripting (XSS) vulnerability in SourceCodester Inventory Management System 1.0. The flaw resides in the /api/vendors_handler.php endpoint within the Vendor Management component. Attackers can manipulate an unspecified input parameter to inject script content that executes in the browser of an authenticated user. The issue is classified under CWE-79 and can be triggered remotely over the network. Public proof-of-concept material has been published, lowering the technical barrier for exploitation.

Critical Impact

An authenticated attacker can inject arbitrary JavaScript through the Vendor Management API, enabling session-context script execution and potential theft of user data or hijacking of vendor-management workflows.

Affected Products

• SourceCodester Inventory Management System 1.0
• Vendor Management component (/api/vendors_handler.php)
• Deployments exposing the API endpoint to authenticated users

Discovery Timeline

• 2026-09-14 - CVE-2026-90695 published to NVD
• 2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-90695

Vulnerability Analysis

The vulnerability is a cross-site scripting flaw located in the Vendor Management API handler of SourceCodester Inventory Management System 1.0. The application fails to sanitize or encode user-supplied input processed by /api/vendors_handler.php before returning it in a response context rendered by the browser. An authenticated attacker with low privileges can supply crafted payloads that the application reflects back or stores, resulting in script execution under the origin of the vulnerable application. Because exploitation requires user interaction, an attacker typically pairs the payload with a lure that causes a legitimate operator to load the crafted request or view attacker-controlled vendor data.

Root Cause

The root cause is missing output encoding and inadequate input validation on parameters handled by the Vendor Management endpoint. The handler places attacker-controlled data into an HTML or JavaScript context without contextual escaping, satisfying the conditions described in CWE-79. SourceCodester Inventory Management System 1.0 does not enforce a Content Security Policy that would restrict inline script execution.

Attack Vector

Exploitation occurs over the network against an authenticated session with low privileges. The attacker crafts a payload targeting the /api/vendors_handler.php endpoint, then induces a victim to visit a controlled link or view attacker-supplied vendor content. The injected script runs in the victim browser under the application origin, allowing session cookie theft, forced actions inside Vendor Management, or pivoting to other application features accessible to the victim. Refer to the VulDB CVE-2026-90695 Entry and the GitHub Gist PoC Script for technical details of the request pattern.

Detection Methods for CVE-2026-90695

Indicators of Compromise

• HTTP requests to /api/vendors_handler.php containing script tags, javascript: URIs, or common XSS payload markers such as onerror=, onload=, or <svg.
• Unexpected outbound requests from operator browsers to external hosts shortly after loading Vendor Management pages.
• Application log entries showing vendor records containing HTML or JavaScript syntax in name, description, or contact fields.

Detection Strategies

• Deploy a web application firewall rule set that inspects query and body parameters submitted to /api/vendors_handler.php for reflected or stored XSS signatures.
• Correlate authenticated session activity with anomalous DOM behavior such as new script sources or unexpected form submissions in Vendor Management views.
• Perform authenticated dynamic application security testing (DAST) against the Vendor Management API to confirm the presence of the flaw.

Monitoring Recommendations

• Enable verbose access logging on the PHP application server and forward events to a central analytics platform for query-based hunting.
• Alert on repeated 200-response requests to /api/vendors_handler.php originating from a single account with payloads containing HTML metacharacters.
• Track browser-side Content Security Policy violation reports if a policy is deployed as a compensating control.

How to Mitigate CVE-2026-90695

Immediate Actions Required

• Restrict access to the Inventory Management System administrative interface to trusted networks or VPN clients until a fix is applied.
• Audit existing vendor records for stored payloads containing HTML or script content and sanitize or remove offending entries.
• Rotate credentials and invalidate active sessions for accounts that may have interacted with malicious vendor data.

Patch Information

No vendor patch is referenced in the enriched CVE data at the time of publication. Administrators should monitor SourceCodester Security Resources for updates and review the VulDB Vulnerability #403228 entry for advisory changes.

Workarounds

• Apply server-side output encoding in vendors_handler.php so that vendor field values are HTML-escaped before being emitted in responses.
• Enforce a strict Content Security Policy that disallows inline script execution and restricts script sources to trusted origins.
• Add input validation that rejects vendor field values containing <, >, or javascript: sequences at the API boundary.

# Configuration example: nginx WAF-style block for suspicious payloads
location = /api/vendors_handler.php {
    if ($args ~* "(<script|onerror=|onload=|javascript:)") {
        return 403;
    }
    if ($request_body ~* "(<script|onerror=|onload=|javascript:)") {
        return 403;
    }
    add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'";
    proxy_pass http://php_backend;
}