CVE-2025-59136 is a vulnerability classified under CWE-201, which involves the insertion of sensitive information into sent data within the Efí Bank Gerencianet Oficial application. This flaw allows an attacker to retrieve embedded sensitive data that is unintentionally included in outbound communications by the application. The affected product versions include all up to 3.1.3, though the exact range is unspecified. The vulnerability is exploitable remotely over the network without requiring any privileges or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact is limited to confidentiality, with no effect on integrity or availability. This suggests that sensitive data such as personal or financial information could be exposed to unauthorized parties during transmission, potentially leading to data leakage or privacy violations. No known exploits have been reported in the wild, and no official patches have been released yet. The vulnerability was reserved in September 2025 and published at the end of 2025, indicating it is a recent discovery. Given the nature of the banking software, the exposure of sensitive data could undermine customer trust and regulatory compliance, especially under stringent European data protection laws like GDPR. The lack of patches necessitates interim mitigations to monitor and control sensitive data flows until a vendor fix is available.

For European organizations, the primary impact of CVE-2025-59136 is the potential unauthorized disclosure of sensitive financial or personal data transmitted by the Gerencianet Oficial banking application. This could lead to privacy breaches, regulatory non-compliance (notably GDPR), reputational damage, and potential financial fraud if attackers intercept or misuse exposed data. Since the vulnerability does not affect data integrity or system availability, the risk is focused on confidentiality loss. Financial institutions and their customers are particularly at risk, as exposed data could include transaction details, account information, or authentication tokens. The ease of exploitation without authentication or user interaction increases the threat level, especially in environments where network traffic is insufficiently monitored or encrypted. European banks and fintech companies using this software may face increased scrutiny from regulators and customers if data leakage occurs. Additionally, the exposure of sensitive data could facilitate further attacks such as phishing or social engineering targeting affected users.

1. Implement network-level data loss prevention (DLP) solutions to detect and block transmission of sensitive information that should not be exposed. 2. Enforce strict encryption of all data in transit using strong protocols (e.g., TLS 1.3) to reduce the risk of interception. 3. Monitor outbound traffic from Gerencianet Oficial instances for anomalous or unexpected data patterns indicative of sensitive data leakage. 4. Restrict network access to the banking application servers to trusted IP ranges and use segmentation to limit exposure. 5. Engage with Efí Bank to obtain timelines for official patches and apply updates promptly once available. 6. Conduct regular security audits and penetration tests focusing on data leakage vectors in the application. 7. Educate staff and customers about the potential risks and encourage vigilance for suspicious activity. 8. Consider deploying application-layer firewalls or proxies that can inspect and sanitize outgoing data streams. 9. Review and minimize the amount of sensitive data embedded in communications wherever possible. 10. Prepare incident response plans specific to data leakage scenarios to enable rapid containment and notification.