CVE-2025-11189 is a reflected cross-site scripting (XSS) vulnerability identified in Synchroweb's Kiwire Captive Portal version 3.6. The vulnerability arises from improper neutralization of input in the login-url parameter during web page generation, classified under CWE-79. This flaw allows an attacker to craft a malicious URL containing JavaScript code that, when accessed by a victim, executes within the victim's browser context. The vulnerability does not require any authentication or user interaction, making it easier to exploit remotely. The CVSS v3.1 base score is 7.3, indicating a high severity level, with attack vector network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and impacts on confidentiality, integrity, and availability (C:L/I:L/A:L). Exploitation could lead to session hijacking, credential theft, unauthorized actions on behalf of the user, or redirection to malicious websites. Although no public exploits are currently known, the vulnerability's characteristics suggest it could be weaponized quickly. The affected product, Kiwire, is used to manage captive portals for Wi-Fi access, commonly deployed in public venues, enterprises, and service providers. This makes the vulnerability particularly concerning for environments where captive portals are used to authenticate users before granting network access. The lack of available patches at the time of publication necessitates immediate attention to input validation and other mitigations to reduce risk.

For European organizations, the impact of CVE-2025-11189 can be significant, especially for those relying on Kiwire captive portals to manage network access in public or private Wi-Fi environments such as airports, hotels, universities, and corporate campuses. Exploitation could allow attackers to execute arbitrary JavaScript in users' browsers, leading to theft of login credentials, session tokens, or other sensitive information. This could result in unauthorized network access, data breaches, or further lateral movement within the network. The integrity of user sessions and availability of captive portal services could also be compromised, potentially disrupting business operations and damaging organizational reputation. Given the critical role of captive portals in access control, a successful attack could undermine trust in network security and expose organizations to regulatory penalties under GDPR if personal data is compromised. The vulnerability's ease of exploitation and lack of required authentication increase the risk of widespread attacks, particularly in environments with high user turnover and public access.

1. Immediate monitoring for any suspicious activity involving the login-url parameter in Kiwire captive portals. 2. Implement strict input validation and sanitization on the login-url parameter to neutralize any injected scripts, using allowlists and encoding techniques. 3. Deploy or update Web Application Firewalls (WAFs) with rules specifically targeting reflected XSS patterns related to captive portal URLs. 4. Restrict or sanitize URL parameters at the network edge or proxy level to prevent malicious payloads from reaching the captive portal. 5. Educate users and administrators about the risks of clicking on suspicious links related to captive portals. 6. Coordinate with Synchroweb for timely patch releases and apply updates as soon as they become available. 7. Conduct regular security assessments and penetration testing focused on captive portal components to identify and remediate similar vulnerabilities. 8. Consider implementing Content Security Policy (CSP) headers to limit the execution of unauthorized scripts within captive portal pages.