CVE-2025-41346 is an authorization bypass vulnerability classified under CWE-863, affecting WinPlus version 24.11.27 developed by Informática del Este. The vulnerability arises from faulty authorization controls that permit an attacker to impersonate any user by simply knowing their numerical user ID. This bypass requires no authentication or user interaction, making exploitation straightforward over the network. Once exploited, the attacker gains full access to the victim’s account, enabling unauthorized data access, modification, or deletion, thereby compromising confidentiality, integrity, and availability of the application’s data. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H) reflects that the attack can be launched remotely with low complexity and no privileges or interaction, and results in high impact on all security properties. Although no public exploits have been reported yet, the critical nature of the flaw demands urgent attention. The vulnerability affects only version 24.11.27 of WinPlus, so organizations running this version are at risk. The lack of available patches at the time of publication increases exposure. The vulnerability was reserved in April 2025 and published in November 2025, indicating recent discovery and disclosure. Given the nature of the flaw, attackers could leverage it for lateral movement, data theft, or sabotage within affected environments.

For European organizations, this vulnerability poses a severe risk, especially those relying on WinPlus for critical business operations or sensitive data management. Successful exploitation can lead to unauthorized access to confidential information, data tampering, and potential service disruption. This could result in regulatory non-compliance under GDPR due to data breaches, financial losses, reputational damage, and operational downtime. Sectors such as finance, healthcare, manufacturing, and government agencies using WinPlus are particularly vulnerable. The ease of exploitation without authentication or user interaction increases the likelihood of attacks, including automated scanning and exploitation by threat actors. The absence of known exploits currently provides a window for proactive defense, but the critical severity score underscores the urgency for mitigation. The vulnerability could also be leveraged in targeted attacks or espionage campaigns against European entities.

1. Immediately restrict network access to WinPlus instances to trusted internal networks and VPNs only, minimizing exposure to external attackers. 2. Implement strict monitoring and logging of user activities within WinPlus to detect anomalous access patterns, especially attempts to access accounts by numerical ID. 3. Enforce multi-factor authentication (MFA) at the application or network level to add an additional layer of security, even though the vulnerability bypasses authorization. 4. Coordinate with Informática del Este for timely patch deployment once available; prioritize patching of all affected systems running version 24.11.27. 5. Conduct an inventory audit to identify all WinPlus installations and verify versions to ensure no vulnerable instances remain unpatched. 6. Apply network segmentation to isolate WinPlus servers from other critical infrastructure to limit lateral movement in case of compromise. 7. Educate IT and security teams about this vulnerability and establish incident response plans tailored to potential exploitation scenarios. 8. Consider deploying Web Application Firewalls (WAF) or Intrusion Detection/Prevention Systems (IDS/IPS) with custom rules to detect and block exploitation attempts targeting numerical ID parameters.