CVE-2025-40719: Quiter Gateway XSS Vulnerability

CVE-2025-40719 Overview

CVE-2025-40719 is a reflected Cross-Site Scripting (XSS) vulnerability affecting Quiter Gateway by Quiter in versions prior to 4.7.0. The flaw resides in the /<Client>FacturaE/VerFacturaPDF endpoint, where the id_concesion parameter is reflected into the response without proper sanitization. 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
Attackers can execute arbitrary JavaScript in a victim's browser, enabling session theft, credential harvesting, and unauthorized actions within the Quiter Gateway application.

Affected Products

Quiter Gateway versions prior to 4.7.0
Vendor: Quiter
Component: quiter:quiter_gateway

Discovery Timeline

2025-07-08 - CVE-2025-40719 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-40719

Vulnerability Analysis

The vulnerability is a reflected XSS flaw located in the VerFacturaPDF handler of the Quiter Gateway application. The endpoint accepts the id_concesion query parameter and reflects its value directly into the HTTP response without applying output encoding or input validation. An attacker who convinces a user to click a crafted link can inject arbitrary HTML and JavaScript that executes within the origin of the Quiter Gateway instance. Because the payload runs in the victim's authenticated context, adversaries can steal cookies, hijack sessions, perform actions on behalf of the user, or pivot to internal application data. Exploitation requires user interaction, as indicated by the UI:A component of the vector.

Root Cause

The underlying weakness is improper neutralization of user-controllable input during web page generation, classified as [CWE-79]. The id_concesion parameter passed to /<Client>FacturaE/VerFacturaPDF is embedded into HTML output without contextual escaping. The application trusts client-supplied query string data and renders it directly, allowing HTML and script tokens supplied by an attacker to be interpreted by the browser rather than displayed as literal text.

Attack Vector

Exploitation follows the standard reflected XSS pattern. The attacker crafts a URL targeting the affected Quiter Gateway instance, embedding a JavaScript payload inside the id_concesion parameter. The victim, typically an authenticated Quiter Gateway user, is lured into clicking the link through phishing, social engineering, or a malicious referrer. When the request reaches /<Client>FacturaE/VerFacturaPDF, the server echoes the payload into the response, and the browser executes it under the application origin. No authentication is required from the attacker to construct the malicious URL.

No verified public proof-of-concept code is available. Technical details are described in the INCIBE Security Notice.

Detection Methods for CVE-2025-40719

Indicators of Compromise

Web server access logs containing requests to /<Client>FacturaE/VerFacturaPDF with suspicious characters such as <script, onerror=, javascript:, or URL-encoded equivalents (%3Cscript) in the id_concesion parameter.
Outbound requests from user browsers to attacker-controlled domains immediately after visiting the VerFacturaPDF endpoint.
Unexpected session cookie exfiltration or unusual authenticated actions originating from legitimate user sessions.

Detection Strategies

Deploy Web Application Firewall (WAF) rules that flag HTML tags, event handlers, and script schemes appearing in the id_concesion query parameter.
Perform log analysis on the Quiter Gateway reverse proxy or application server for anomalous URL patterns targeting VerFacturaPDF.
Correlate authentication logs with access log spikes to identify sessions that received reflected payloads.

Monitoring Recommendations

Enable and centralize HTTP request logging for all Quiter Gateway endpoints, retaining full query strings.
Alert on any request to VerFacturaPDF containing angle brackets, backticks, or common XSS keywords after URL decoding.
Monitor for phishing campaigns referencing the Quiter Gateway domain in threat intelligence feeds.

How to Mitigate CVE-2025-40719

Immediate Actions Required

Upgrade Quiter Gateway to version 4.7.0 or later, which addresses the reflected XSS in the VerFacturaPDF endpoint.
Inventory all Quiter Gateway deployments across the environment and confirm patched status against the vendor's fixed release.
Notify users of the risk and instruct them to avoid clicking untrusted links referencing the Quiter Gateway application.

Patch Information

Quiter has resolved the vulnerability in Quiter Gateway version 4.7.0. Administrators should review the INCIBE Security Notice for the complete list of related fixes and upgrade instructions.

Workarounds

Restrict access to the Quiter Gateway application to trusted networks or through a VPN until patching is complete.
Configure a WAF rule to block or sanitize requests to /<Client>FacturaE/VerFacturaPDF that contain HTML metacharacters in the id_concesion parameter.
Enforce a strict Content-Security-Policy response header that disallows inline scripts and restricts script sources to trusted origins.

bash

# Example nginx WAF-style rule to block XSS patterns in id_concesion
location ~* /FacturaE/VerFacturaPDF {
    if ($arg_id_concesion ~* "(<|%3C)\s*script|javascript:|onerror=|onload=") {
        return 403;
    }
    add_header Content-Security-Policy "default-src 'self'; script-src 'self'" always;
    proxy_pass http://quiter_backend;
}