CVE-2025-54490 is a critical stack-based buffer overflow vulnerability identified in The Biosig Project's libbiosig library, specifically affecting versions 3.9.0 and the current master branch (commit 35a819fa). The vulnerability resides in the MFER file parsing functionality, where a specially crafted MFER file can trigger a buffer overflow condition. The root cause is located in biosig.c at line 9090, where the code reads data into a fixed-size stack buffer named 'tmp' of 256 bytes without adequately validating the length 'len' of the input data. If 'len' is encoded using multiple octets and exceeds 256 bytes, the buffer 'tmp' is overflowed, leading to memory corruption on the stack. This flaw allows an attacker to execute arbitrary code remotely by supplying a malicious MFER file to an application that uses libbiosig for MFER parsing. The vulnerability has a CVSS v3.1 score of 9.8, indicating critical severity, with an attack vector of network (AV:N), no privileges required (PR:N), no user interaction (UI:N), and full impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No known exploits are currently reported in the wild, but the ease of exploitation and the critical impact make this a high-risk issue. The Biosig Project is an open-source library used for biosignal processing, including EEG, ECG, and other physiological signal analysis, and is integrated into various research and medical software tools. The vulnerability's exploitation could lead to complete system compromise of affected applications processing untrusted MFER files.

For European organizations, the impact of CVE-2025-54490 can be significant, especially in sectors relying on biosignal processing software that incorporates libbiosig, such as healthcare, biomedical research, and medical device manufacturers. Exploitation could lead to arbitrary code execution on systems processing malicious MFER files, potentially resulting in data breaches involving sensitive patient or research data, disruption of critical medical analysis workflows, and compromise of system integrity. Given the critical severity and network attack vector, attackers could remotely exploit vulnerable systems without authentication or user interaction, increasing the risk of widespread impact. Healthcare providers and research institutions in Europe that utilize software dependent on libbiosig may face operational disruptions and regulatory compliance issues under GDPR if patient data confidentiality is breached. Furthermore, compromised systems could be leveraged as entry points for broader network intrusions, affecting organizational IT infrastructure and critical services.

To mitigate this vulnerability effectively, European organizations should: 1) Immediately identify all software and systems using libbiosig versions 3.9.0 or the affected master branch, including custom and third-party applications processing MFER files. 2) Apply patches or updates from The Biosig Project as soon as they become available; if no official patch exists yet, consider temporarily disabling MFER file parsing or restricting input sources to trusted files only. 3) Implement strict input validation and sandboxing for applications handling MFER files to contain potential exploitation attempts. 4) Employ network-level protections such as intrusion detection/prevention systems (IDS/IPS) configured to detect anomalous MFER file traffic or malformed payloads. 5) Conduct thorough code audits and penetration testing on software components integrating libbiosig to identify and remediate similar unsafe buffer handling practices. 6) Educate developers and system administrators about secure coding practices to prevent buffer overflows and ensure timely vulnerability management. 7) Monitor security advisories from The Biosig Project and related communities for updates and exploit reports.