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 improper authorization controls that allow an attacker to impersonate another user by simply knowing their numerical user ID. This bypass does not require any authentication, privileges, or user interaction, making exploitation straightforward. Once impersonation is achieved, the attacker gains access to the victim's account, enabling unauthorized access to sensitive data, modification of information, and disruption of services within the application. The vulnerability impacts confidentiality, integrity, and availability (CIA triad) of the data managed by WinPlus. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N) reflects that the attack can be performed remotely over the network with low complexity and no prerequisites, resulting in high impact on all security properties. Although no public exploits are currently reported, the simplicity of the attack vector and the critical nature of the flaw make it a significant threat. WinPlus is used in various sectors, potentially including critical infrastructure and enterprise environments, increasing the risk profile. The lack of available patches at the time of publication necessitates immediate risk mitigation through compensating controls and monitoring.

For European organizations, this vulnerability poses a severe risk of unauthorized access to sensitive business and personal data, potentially leading to data breaches, regulatory non-compliance (e.g., GDPR violations), and reputational damage. The ability to impersonate users without authentication can facilitate insider-like attacks, fraud, and sabotage. Integrity of data can be compromised by unauthorized modifications, while availability may be affected if attackers disrupt services or delete critical information. Organizations in sectors such as finance, healthcare, government, and critical infrastructure using WinPlus are particularly vulnerable. The breach of confidentiality and integrity could lead to significant operational and financial consequences, including fines and loss of customer trust. The ease of exploitation increases the likelihood of attacks, especially if user IDs are predictable or exposed. Additionally, the lack of known exploits currently provides a narrow window for proactive defense before potential attackers develop and deploy exploit code.

1. Immediately restrict access to user numerical IDs within the organization to minimize exposure. 2. Implement strict network segmentation and access controls around WinPlus servers to limit potential attackers' ability to reach the vulnerable service. 3. Monitor logs and user activity for unusual access patterns or impersonation attempts, focusing on anomalies involving user ID usage. 4. Employ multi-factor authentication (MFA) at the application or network level to add an additional layer of verification, even if the application itself lacks it. 5. Coordinate with Informática del Este for timely release and deployment of official patches or updates addressing this vulnerability. 6. Until patches are available, consider deploying Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with custom rules to detect and block suspicious requests involving user ID impersonation attempts. 7. Conduct user awareness training to recognize and report suspicious account activity. 8. Review and tighten authorization logic in custom integrations or extensions of WinPlus to prevent similar flaws. 9. Prepare incident response plans specifically for potential exploitation scenarios involving this vulnerability.