CVE-2025-41350 is a stored Cross-site Scripting (XSS) vulnerability identified in version 24.11.27 of WinPlus, a product developed by Informática del Este. The vulnerability stems from improper neutralization of user input during web page generation, specifically in the handling of the 'descripcion' parameter submitted via a POST request to the '/WinplusPortal/ws/sWinplus.svc/json/savesoldoc_post' endpoint. Because the input is not properly validated or sanitized, an attacker with authenticated access can inject malicious JavaScript code that is stored on the server and subsequently executed in the browsers of other authenticated users who view the affected content. This can lead to theft of session cookies, enabling session hijacking and unauthorized actions within the application context. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L - low privileges), user interaction required (UI:P), and limited scope and impact on confidentiality, integrity, and availability (VC:N, VI:N, VA:N). Although no public exploits are currently known, the vulnerability poses a moderate risk due to the potential for session theft and subsequent unauthorized access. The vulnerability is classified under CWE-79, which covers improper neutralization of input leading to XSS attacks. Since the flaw requires authentication and user interaction, exploitation is somewhat limited but still significant in environments where multiple users have access to the system. The lack of an official patch at the time of publication necessitates immediate mitigation steps by affected organizations.

For European organizations, the impact of CVE-2025-41350 can be significant, particularly in sectors relying on WinPlus for critical business operations such as manufacturing, logistics, or enterprise resource planning. Successful exploitation can lead to session hijacking, allowing attackers to impersonate legitimate users, potentially accessing sensitive data or performing unauthorized transactions. This undermines confidentiality and integrity of organizational data and can disrupt business continuity. Given the medium severity and the requirement for user interaction and authentication, the risk is higher in environments with many users and less stringent access controls. Additionally, organizations with remote or hybrid workforces may face increased exposure if attackers can lure authenticated users into triggering the malicious payload. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits over time. The vulnerability could also be leveraged as a foothold for further attacks within the network, increasing overall risk posture.

European organizations using WinPlus version 24.11.27 should immediately audit their deployments to identify affected instances. Until an official patch is released, implement strict input validation and sanitization on the 'descripcion' parameter at the application or web server level to neutralize potentially malicious scripts. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Enforce least privilege principles to limit user permissions, reducing the impact of compromised accounts. Monitor logs for unusual POST requests to the vulnerable endpoint and suspicious user behavior indicative of exploitation attempts. Educate users about phishing and social engineering tactics that could trigger malicious payloads. Coordinate with Informática del Este for timely patch updates and apply them promptly once available. Consider deploying Web Application Firewalls (WAF) with custom rules to detect and block XSS payloads targeting this endpoint. Regularly review and update security policies to incorporate lessons learned from this vulnerability.