CVE-2025-40719 is a reflected Cross-site Scripting (XSS) vulnerability affecting versions prior to 4.7.0 of the Quiter Gateway product, which is a Java WAR application running on Apache Tomcat. The vulnerability arises from improper neutralization of user-supplied input during web page generation, specifically in the handling of the 'id_concesion' parameter within the /<Client>FacturaE/VerFacturaPDF endpoint. An attacker can craft a malicious URL containing JavaScript code embedded in this parameter, which, when visited by a victim, causes the victim's browser to execute the injected script. This reflected XSS does not require authentication and can be exploited remotely by simply enticing a user to click a malicious link. The CVSS 4.0 base score is 5.1 (medium severity), reflecting that the attack vector is network-based with low attack complexity, no privileges or user interaction required, but the impact on confidentiality, integrity, and availability is limited. The vulnerability is categorized under CWE-79, indicating improper input neutralization leading to script injection. No known exploits are currently reported in the wild, and no patches are linked yet, suggesting the vulnerability is newly disclosed. The Quiter Gateway product is used for document management or invoicing workflows (as inferred from the FacturaE endpoint), likely in enterprise or governmental environments.

For European organizations, this vulnerability poses a risk primarily to the confidentiality and integrity of user sessions and data accessed via the Quiter Gateway interface. Successful exploitation could allow attackers to execute arbitrary JavaScript in the context of the victim's browser, potentially leading to session hijacking, credential theft, unauthorized actions on behalf of the user, or redirection to malicious sites. Given that Quiter Gateway is deployed on Apache Tomcat and used for handling invoicing or client document workflows, exploitation could disrupt business processes or leak sensitive financial data. The reflected XSS nature means attacks require user interaction (clicking a malicious link), but phishing campaigns targeting employees or partners could be effective. While availability impact is minimal, the reputational damage and compliance risks (e.g., GDPR implications from data leakage) are significant. The medium CVSS score reflects these moderate but non-trivial risks. Organizations relying on Quiter Gateway should consider this a priority vulnerability to address to maintain secure web application operations.

1. Immediate mitigation involves updating the Quiter Gateway software to version 4.7.0 or later once available, as this version presumably contains the fix for this XSS vulnerability. 2. Until patching is possible, implement Web Application Firewall (WAF) rules to detect and block malicious payloads targeting the 'id_concesion' parameter, focusing on suspicious JavaScript patterns or encoded scripts. 3. Conduct input validation and output encoding on all user-supplied parameters, especially those reflected in web pages, to neutralize script injection vectors. 4. Employ Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of XSS attacks. 5. Educate users and staff about phishing risks and the dangers of clicking untrusted links, as user interaction is required for exploitation. 6. Monitor web server and application logs for unusual requests to the vulnerable endpoint that may indicate exploitation attempts. 7. Review and harden session management to limit the impact of session hijacking if an XSS attack succeeds. 8. Coordinate with Quiter support or vendor channels to obtain official patches or workarounds promptly.