CVE-2025-42604 is a medium-severity vulnerability affecting Meon KYC (Know Your Customer) solutions, specifically version 1.1. The root cause of this vulnerability is that debug mode is enabled on certain API endpoints within the affected product. When debug mode is active, the API endpoints return detailed error messages that include system-related information. These messages can inadvertently disclose sensitive internal details such as software versions, configuration data, stack traces, or other diagnostic information. A remote attacker can exploit this vulnerability by sending unauthorized requests to these API endpoints and receiving verbose debug responses. This information disclosure can aid attackers in reconnaissance activities, helping them to identify potential weaknesses or plan further targeted attacks. The vulnerability is classified under CWE-1295, which relates to debug messages revealing unnecessary information. There are no known exploits in the wild at the time of publication, and no patches have been released yet. The vulnerability was reserved and published in April 2025, with CERT-In and CISA involvement in enrichment and assignment. Since the debug mode is enabled on unauthorized API endpoints, this indicates a misconfiguration or oversight in secure development and deployment practices. The vulnerability does not require authentication or user interaction, increasing its risk profile. However, the impact is limited to information disclosure rather than direct code execution or privilege escalation.

For European organizations using Meon KYC solutions, this vulnerability poses a risk primarily related to information disclosure. KYC solutions are critical components in financial institutions, fintech companies, and other regulated entities that require identity verification and compliance with anti-money laundering (AML) regulations. Disclosure of internal system details can facilitate more sophisticated attacks such as targeted exploitation, social engineering, or bypassing security controls. While the vulnerability does not directly allow unauthorized access or data manipulation, the leaked debug information can weaken the overall security posture. This is particularly concerning for organizations handling sensitive personal and financial data under strict regulatory frameworks like GDPR. Additionally, attackers could leverage the disclosed information to identify other vulnerabilities or misconfigurations in the environment. The impact on availability and integrity is minimal, but confidentiality risks are moderate. Given the strategic importance of KYC systems in preventing fraud and financial crime, any compromise or reconnaissance advantage can have cascading effects on trust and regulatory compliance.

To mitigate this vulnerability, European organizations should take the following specific actions: 1) Immediately verify and disable debug mode on all API endpoints in Meon KYC solutions, especially those exposed to external or untrusted networks. 2) Conduct a thorough audit of API configurations and logs to ensure no sensitive debug information is being leaked. 3) Implement strict access controls and authentication mechanisms on all API endpoints to prevent unauthorized access. 4) Engage with Meon to obtain patches or updates that address this vulnerability once available, and prioritize their deployment. 5) Employ Web Application Firewalls (WAF) or API gateways with rules to detect and block suspicious requests targeting debug endpoints. 6) Monitor network traffic and application logs for unusual access patterns or attempts to exploit debug endpoints. 7) Train development and operations teams on secure deployment practices to avoid enabling debug modes in production environments. 8) Consider implementing runtime application self-protection (RASP) solutions to detect and prevent information leakage in real time. These measures go beyond generic advice by focusing on configuration hygiene, proactive monitoring, and vendor coordination.