CVE-2025-66048 is a stack-based buffer overflow vulnerability identified in version 3.9.1 of libbiosig, an open-source library used for biosignal processing, including biometric data analysis. The vulnerability resides specifically in the MFER (Medical and Functional Electroencephalogram Recordings) file parsing functionality when processing files containing Tag 133. An attacker can craft a malicious MFER file that triggers the buffer overflow, leading to arbitrary code execution on the host system. This type of vulnerability (CWE-121) occurs when data exceeding the buffer size is copied onto the stack, overwriting control data such as return addresses. The flaw does not require any privileges, authentication, or user interaction, making remote exploitation feasible if the library processes untrusted MFER files. The CVSS v3.1 score of 9.8 reflects the critical nature of the vulnerability, with network attack vector, low attack complexity, and full impact on confidentiality, integrity, and availability. Although no public exploits have been reported yet, the potential for severe damage is significant, especially in environments where libbiosig is integrated into medical or biometric systems. The lack of a current patch necessitates immediate risk mitigation strategies. The vulnerability's exploitation could lead to unauthorized system control, data theft, or disruption of critical biosignal processing operations.

For European organizations, the impact of CVE-2025-66048 is substantial, particularly for those involved in healthcare, biomedical research, and biometric authentication systems that utilize libbiosig. Exploitation could result in unauthorized access to sensitive biometric or medical data, compromising patient privacy and violating GDPR regulations. Integrity of biosignal data could be undermined, leading to incorrect diagnostics or authentication failures. Availability of critical systems could be disrupted, affecting healthcare delivery or security operations. The critical severity and ease of exploitation mean attackers could deploy malware, establish persistent access, or cause denial-of-service conditions. This threat also poses reputational risks and potential legal liabilities for affected organizations. Given the specialized nature of libbiosig, sectors relying on biosignal analysis software are most vulnerable, and the impact could cascade into broader operational disruptions if exploited in critical infrastructure or research facilities.

1. Monitor official Biosig Project channels for patches addressing CVE-2025-66048 and apply updates immediately upon release. 2. Until a patch is available, implement strict input validation and sanitization for all MFER files processed by libbiosig to detect and reject malformed or suspicious files, especially those containing Tag 133. 3. Employ sandboxing or containerization techniques to isolate libbiosig processing environments, limiting the impact of potential exploitation. 4. Restrict network exposure of services or applications that parse MFER files, using firewalls and network segmentation to reduce attack surface. 5. Conduct code audits and penetration testing focused on biosignal processing components to identify and remediate similar vulnerabilities proactively. 6. Implement robust logging and monitoring to detect anomalous behavior indicative of exploitation attempts. 7. Educate developers and system administrators on secure handling of biosignal data and the risks associated with third-party libraries. 8. Consider alternative libraries or solutions with better security track records if immediate patching is not feasible.