CVE-2025-54485 is a critical stack-based buffer overflow vulnerability identified in The Biosig Project's libbiosig library, specifically affecting version 3.9.0 and the current master branch (commit 35a819fa). The vulnerability arises in the MFER (Medical Format for Electroencephalogram Recordings) parsing functionality. The flaw occurs when processing MFER files containing a tag with the value 8, where the length check is insufficient to prevent buffer overflow. Specifically, on line 8785 of biosig.c, the code reads data into a buffer without adequately validating the length, allowing an attacker to craft a malicious MFER file that triggers a stack overflow. This can lead to arbitrary code execution without requiring any user interaction or privileges, as the CVSS vector indicates. The vulnerability impacts confidentiality, integrity, and availability, making it highly severe. Although no known exploits are currently reported in the wild, the high CVSS score of 9.8 reflects the ease of exploitation and the potential for significant damage. The vulnerability is categorized under CWE-121, which relates to stack-based buffer overflows, a common and dangerous class of memory corruption bugs. Given libbiosig's role in processing biomedical signal data, this vulnerability could be exploited to compromise systems handling sensitive medical data or critical healthcare infrastructure.

For European organizations, the impact of this vulnerability is substantial, especially for those involved in healthcare, biomedical research, and medical device manufacturing that utilize libbiosig for processing biomedical signals. Exploitation could lead to unauthorized code execution, enabling attackers to steal sensitive patient data, manipulate medical records, or disrupt medical device operations, potentially endangering patient safety. The compromise of confidentiality and integrity of medical data also raises compliance risks under GDPR and other data protection regulations. Additionally, availability impacts could disrupt healthcare services relying on affected systems. Given the critical nature of healthcare infrastructure in Europe, successful exploitation could have cascading effects on public health services and trust in medical technology providers.

Organizations should immediately identify and inventory all systems and applications using libbiosig version 3.9.0 or the affected master branch. Since no official patches are currently available, it is recommended to implement the following mitigations: 1) Employ strict input validation and sandboxing for any MFER file processing to limit the impact of malformed files. 2) Use runtime protections such as stack canaries, Address Space Layout Randomization (ASLR), and Data Execution Prevention (DEP) to mitigate exploitation risk. 3) Monitor network and system logs for anomalous activity related to MFER file handling. 4) Engage with The Biosig Project or maintainers to obtain or contribute patches that properly validate input lengths and prevent buffer overflows. 5) Where feasible, isolate systems processing MFER files from critical networks to reduce attack surface. 6) Educate staff about the risks of handling untrusted biomedical data files and enforce strict file provenance policies. These targeted steps go beyond generic advice by focusing on the specific context of MFER file processing and the medical domain.