CVE-2025-54486 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 (Multi-Format Electroencephalogram Recording) file parsing functionality, particularly when processing a tag with the value 11 (0x0B). The flaw occurs at line 8824 in biosig.c, where the code reads data from a buffer without adequate bounds checking. If the length of the data exceeds expected limits (greater than 6 bytes), the code issues a warning but does not prevent the overflow. This unchecked buffer operation allows an attacker to craft a malicious MFER file that, when parsed by libbiosig, can overwrite the stack, leading to arbitrary code execution. The vulnerability requires no privileges or user interaction and can be exploited remotely by supplying a malicious file to an application using the vulnerable libbiosig library. The CVSS v3.1 base score is 9.8, reflecting its critical severity with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The impact includes full compromise of confidentiality, integrity, and availability of the affected system. Currently, no public exploits are known, and no patches have been linked yet, indicating that mitigation may rely on vendor updates or workarounds. Given libbiosig's role in processing biosignal data, this vulnerability poses a significant risk to applications handling sensitive biomedical data.

For European organizations, the impact of CVE-2025-54486 is substantial, especially for entities involved in healthcare, biomedical research, and medical device manufacturing that utilize biosignal processing software incorporating libbiosig. Exploitation could lead to remote code execution, enabling attackers to gain unauthorized access to sensitive patient data, disrupt medical research workflows, or manipulate medical device outputs. This could result in severe privacy violations under GDPR, operational downtime, and potential harm to patients if medical devices are compromised. Additionally, organizations relying on biosignal data for diagnostics or research may face data integrity issues, undermining trust and compliance with regulatory standards. The critical nature of this vulnerability demands urgent attention to prevent exploitation that could cascade into broader network compromises or targeted attacks against healthcare infrastructure in Europe.

1. Immediate mitigation should involve auditing all software and systems that utilize libbiosig version 3.9.0 or the affected master branch for MFER file parsing capabilities. 2. Until an official patch is released, implement strict input validation and sandboxing of any process handling MFER files to contain potential exploitation. 3. Employ application-level whitelisting to restrict execution of untrusted files and monitor for anomalous behavior indicative of exploitation attempts. 4. Coordinate with software vendors and open-source maintainers to prioritize patch development and deployment. 5. For organizations developing custom applications with libbiosig, consider backporting or applying manual bounds checking fixes around the vulnerable code segment to prevent buffer overflow. 6. Enhance network security controls to limit exposure of systems processing biosignal data, including segmentation and access controls. 7. Maintain up-to-date intrusion detection and prevention systems with signatures tuned to detect exploitation patterns related to this vulnerability. 8. Educate relevant staff about the risks of processing untrusted MFER files and enforce strict file handling policies.