CVE-2025-40721: Quiter Gateway XSS Vulnerability

CVE-2025-40721 Overview

CVE-2025-40721 is a reflected Cross-Site Scripting (XSS) vulnerability affecting Quiter Gateway versions prior to 4.7.0. The flaw resides in the id_factura parameter of the /<Client>FacturaE/listado_facturas_ficha.jsp endpoint. An attacker can craft a malicious URL that, when opened by an authenticated victim, executes arbitrary JavaScript in the victim's browser session. The issue is tracked under CWE-79 and was disclosed through an INCIBE Security Notice.

Critical Impact
Successful exploitation allows attackers to hijack sessions, steal credentials, or perform actions in the context of the authenticated Quiter Gateway user.

Affected Products

Quiter Gateway versions prior to 4.7.0
Quiter QuiterWeb (per associated INCIBE advisory)
Quiter AutoWeb (per associated INCIBE advisory)

Discovery Timeline

2025-07-08 - CVE-2025-40721 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2025-40721

Vulnerability Analysis

The vulnerability is a reflected XSS flaw in the Quiter Gateway web interface. The listado_facturas_ficha.jsp page accepts the id_factura query parameter and reflects its value into the HTTP response without proper output encoding or input sanitization. As a result, attacker-supplied script content included in the URL executes in the victim's browser under the origin of the Quiter Gateway application. Because the attack targets active user sessions, an attacker leveraging this flaw can act on behalf of the victim within the Quiter Gateway application, including reading displayed invoice data or manipulating client-side workflows.

Root Cause

The root cause is missing neutralization of user-controlled input during web page generation (CWE-79). The id_factura parameter value is embedded into the rendered JSP output without HTML entity encoding or contextual escaping. The application does not validate that id_factura conforms to an expected numeric or identifier format before echoing it back to the browser.

Attack Vector

Exploitation requires user interaction. The attacker crafts a URL targeting the vulnerable endpoint with a JavaScript payload placed in the id_factura parameter, for example within /<Client>FacturaE/listado_facturas_ficha.jsp?id_factura=<payload>. The attacker then delivers the URL to a victim through phishing email, chat, or a malicious webpage. When the victim, typically an authenticated Quiter Gateway user, opens the link, the payload executes in the browser under the application's origin. Refer to the INCIBE Security Notice for further technical details.

Detection Methods for CVE-2025-40721

Indicators of Compromise

HTTP requests to /<Client>FacturaE/listado_facturas_ficha.jsp containing id_factura values with HTML tags, <script>, javascript:, onerror=, or URL-encoded equivalents such as %3Cscript%3E.
Referer headers pointing to untrusted external domains for sessions accessing the invoice listing endpoint.
Unexpected outbound browser requests from users after visiting a Quiter Gateway URL, indicating potential payload beaconing.

Detection Strategies

Deploy web application firewall (WAF) rules that inspect the id_factura parameter for script tags, event handlers, and encoded XSS payloads.
Enable web server access logging and alert on anomalously long id_factura values or values containing angle brackets and quotes.
Correlate JSP request logs with browser-side Content Security Policy (CSP) violation reports to identify attempted script execution.

Monitoring Recommendations

Monitor authentication events immediately following user access to listado_facturas_ficha.jsp for anomalous session creation or credential reuse.
Track outbound HTTP requests from user endpoints for connections to unfamiliar domains that could serve as data exfiltration channels.
Review Quiter Gateway user activity for actions that occur without corresponding user interaction, which may indicate hijacked sessions.

How to Mitigate CVE-2025-40721

Immediate Actions Required

Upgrade Quiter Gateway to version 4.7.0 or later as advised by the vendor.
Inform Quiter Gateway users to avoid clicking on unsolicited links referencing the application, particularly URLs containing the id_factura parameter.
Rotate active user sessions and invalidate cookies for accounts suspected of exposure to malicious URLs.

Patch Information

Quiter has addressed the vulnerability in Quiter Gateway version 4.7.0. Organizations should consult the INCIBE Security Notice for full patch details covering the related QuiterWeb and AutoWeb products.

Workarounds

Deploy a WAF rule to block or sanitize requests where id_factura contains characters such as <, >, ", ', or the string script.
Configure a strict Content Security Policy (CSP) on the Quiter Gateway host to restrict inline script execution and untrusted script sources.
Restrict access to the /<Client>FacturaE/ path to trusted internal networks or VPN users until patching is complete.

bash

# Example ModSecurity rule to block XSS payloads in id_factura parameter
SecRule ARGS:id_factura "@rx (?i)(<script|javascript:|onerror=|onload=|%3Cscript)" \
    "id:1040721,\
    phase:2,\
    deny,\
    status:403,\
    log,\
    msg:'CVE-2025-40721 - Reflected XSS attempt in Quiter Gateway id_factura parameter'"