CVE-2025-54481 is a stack-based buffer overflow vulnerability identified in the MFER parsing functionality of The Biosig Project's libbiosig library, specifically in versions 3.9.0 and the master branch (commit 35a819fa). The vulnerability arises from improper bounds checking when reading character data tagged as '3' into a fixed-size buffer 'v' of 17 bytes. The code reads 'len' bytes from the input file into 'v' without adequately ensuring that 'len' does not exceed the buffer size, leading to a buffer overflow on the stack. This overflow can corrupt adjacent memory, potentially allowing an attacker to execute arbitrary code with the privileges of the application using libbiosig. The vulnerability is triggered by supplying a maliciously crafted MFER file, a format used for biosignal data. The flaw is located at line 8744 in biosig.c, where the code attempts to read and null-terminate the buffer without sufficient length validation. The CVSS v3.1 base score is 9.8, reflecting the vulnerability's critical nature due to network attack vector, no required privileges or user interaction, and full impact on confidentiality, integrity, and availability. No public exploits are known yet, but the vulnerability's characteristics make it highly exploitable once weaponized. The Biosig Project is a widely used open-source library in biosignal processing applications, including medical devices and biometric systems, which increases the potential attack surface.

For European organizations, the impact of CVE-2025-54481 can be severe, particularly in sectors relying on biosignal processing such as healthcare, biometric authentication, and research institutions. Exploitation could lead to arbitrary code execution, enabling attackers to compromise system confidentiality, integrity, and availability. This could result in unauthorized access to sensitive patient data, manipulation of biometric authentication systems, or disruption of critical medical devices and research operations. Given the critical CVSS score and the lack of required authentication or user interaction, attackers could remotely exploit vulnerable systems by delivering malicious MFER files, potentially through network services or file-sharing mechanisms. The disruption or compromise of healthcare and biometric systems could have cascading effects on patient safety, privacy compliance (e.g., GDPR), and operational continuity. Additionally, organizations may face regulatory penalties and reputational damage if breaches occur due to this vulnerability.

1. Monitor The Biosig Project's official channels for patches addressing CVE-2025-54481 and apply updates promptly once available. 2. Until patches are released, implement strict input validation to reject MFER files with suspiciously large or malformed tags, especially those with tag '3' and length fields exceeding 16 bytes. 3. Employ sandboxing or isolation techniques for applications processing MFER files to contain potential exploitation attempts. 4. Conduct code audits and static analysis on custom integrations of libbiosig to identify and remediate unsafe parsing practices. 5. Restrict network exposure of services that accept MFER files to trusted sources only, and implement file integrity checks and scanning for malicious payloads. 6. Enhance monitoring and logging around biosignal processing systems to detect anomalous behavior indicative of exploitation attempts. 7. Educate developers and system administrators about this vulnerability to ensure rapid response and mitigation in affected environments.