CVE-2025-41349 is a stored Cross-site Scripting (XSS) vulnerability identified in WinPlus version 24.11.27, 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 POST requests to the '/WinplusPortal/ws/sWinplus.svc/json/savesolpla_post' endpoint. Because the application fails to properly validate or sanitize this input, an attacker with authenticated access can inject malicious JavaScript code that is stored persistently on the server. When other authenticated users access the affected functionality or view the stored data, the malicious script executes in their browsers within the security context of the application. This can lead to theft of session cookies, enabling session hijacking and unauthorized actions on behalf of the victim user. The vulnerability requires the attacker to be authenticated and involves user interaction (victim must access the malicious content). The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N) reflects network attack vector, low attack complexity, no attack or user privileges beyond normal user, and user interaction required. The vulnerability does not affect confidentiality, integrity, or availability directly but compromises session security. No known public exploits or patches are currently available, increasing the importance of proactive mitigation. The vulnerability was reserved in April 2025 and published in November 2025, with INCIBE as the assigner.

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality and session integrity. Attackers who gain authenticated access can inject malicious scripts that compromise other users' sessions, potentially leading to unauthorized access to sensitive data or functionality. This is particularly concerning for organizations relying on WinPlus for critical business operations, as session hijacking can facilitate privilege escalation or data exfiltration. The requirement for authentication limits exposure to insider threats or compromised accounts, but the risk remains significant in environments with many users or weak access controls. The lack of patches or known exploits means organizations must rely on detection and mitigation strategies. Additionally, sectors such as finance, healthcare, and government in Europe that use WinPlus may face increased risk due to the sensitivity of their data and regulatory requirements around data protection and incident response.

To mitigate CVE-2025-41349, organizations should implement strict input validation and sanitization on the 'descripcion' parameter and any other user-supplied data before storage or rendering. Employ context-aware output encoding to prevent script execution in browsers. Enforce the principle of least privilege for user accounts to reduce the impact of compromised credentials. Monitor application logs and network traffic for unusual POST requests targeting the vulnerable endpoint. Use Web Application Firewalls (WAFs) with custom rules to detect and block malicious payloads attempting XSS injection. Educate users about phishing and social engineering risks that could lead to credential compromise. Coordinate with Informática del Este for updates or patches and apply them promptly once available. Consider implementing multi-factor authentication to reduce the risk of unauthorized access. Regularly review and update security policies related to web application security and session management.