CVE-2025-42600 is a vulnerability identified in Meon KYC (Know Your Customer) solutions, specifically version 1.1. The core issue stems from improper restriction of excessive authentication attempts (CWE-307) on certain API endpoints involved in the login process. The vulnerability allows a remote attacker to perform brute force attacks against the One-Time Password (OTP) mechanism by exploiting the lack of rate limiting or lockout mechanisms on incorrect OTP submissions. Since OTPs are a critical component of multi-factor authentication and user verification in KYC workflows, this flaw can enable attackers to systematically guess OTPs until successful authentication is achieved. This unauthorized access could lead to compromise of user accounts, potentially exposing sensitive personal and financial information collected during the KYC process. The vulnerability does not require prior authentication or user interaction, making it accessible remotely. Although no known exploits are currently reported in the wild, the absence of mitigation controls significantly lowers the barrier for exploitation. The vulnerability was reserved on April 16, 2025, and published on April 23, 2025, with a medium severity rating assigned by the vendor. No patches or fixes have been linked yet, indicating that affected organizations may still be vulnerable. The vulnerability is particularly critical given the sensitive nature of KYC data and the regulatory importance of identity verification in financial and other sectors.

For European organizations, the impact of this vulnerability can be substantial, especially for financial institutions, fintech companies, and any service providers relying on Meon KYC solutions for customer onboarding and identity verification. Unauthorized access to user accounts via brute forcing OTPs can lead to identity theft, fraud, and regulatory non-compliance with GDPR and anti-money laundering (AML) directives. The compromise of KYC data can also damage organizational reputation and customer trust. Additionally, attackers gaining access to user accounts may perform fraudulent transactions or manipulate user data, causing financial losses and operational disruptions. Given the critical role of KYC in preventing financial crimes, exploitation of this vulnerability could undermine compliance efforts and invite regulatory penalties. The medium severity rating suggests moderate risk, but the potential for widespread account compromise and data exposure elevates the concern for organizations handling large volumes of sensitive customer data.

Organizations using Meon KYC solutions should implement immediate compensating controls while awaiting official patches. These include: 1) Implementing external rate limiting and account lockout policies on OTP verification endpoints to prevent brute force attempts. 2) Monitoring and alerting on abnormal authentication failure rates to detect potential attacks early. 3) Enforcing multi-factor authentication methods that do not rely solely on OTPs or augmenting OTP with additional verification factors. 4) Conducting regular security assessments and penetration testing focused on authentication mechanisms. 5) Applying network-level protections such as Web Application Firewalls (WAFs) configured to detect and block repeated failed OTP attempts. 6) Educating users about the risks of unauthorized access and encouraging strong password hygiene. 7) Segregating sensitive KYC data access with additional authorization layers. These measures should be implemented promptly to reduce the attack surface until Meon releases a patch addressing the vulnerability.