CVE-2025-54494 is a stack-based buffer overflow vulnerability identified in The Biosig Project's libbiosig library, specifically in versions 3.9.0 and the current master branch (commit 35a819fa). The vulnerability arises in the MFER file parsing code, particularly when processing tag 133 (0x85) in biosig.c at line 9205. The function increments a buffer position pointer (curPos) by reading data from a file into a buffer without adequate bounds checking, allowing an attacker to overflow the stack buffer. This overflow can overwrite the stack frame, enabling arbitrary code execution under the context of the vulnerable application. The vulnerability requires no privileges or user interaction, as it can be triggered simply by processing a maliciously crafted MFER file. The CVSS v3.1 score of 9.8 reflects its critical nature, with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The impact spans confidentiality, integrity, and availability, as arbitrary code execution can lead to data theft, system compromise, or denial of service. While no public exploits are currently reported, the vulnerability's characteristics make it a high-risk target for attackers once exploit code becomes available. The Biosig Project is widely used in biomedical signal processing, meaning affected systems often reside in healthcare, research, and related sectors. The lack of available patches at the time of disclosure necessitates immediate risk mitigation strategies to prevent exploitation.

The vulnerability poses a severe risk to European organizations relying on libbiosig for biomedical signal processing, including hospitals, research institutions, and medical device manufacturers. Exploitation can lead to full system compromise, allowing attackers to execute arbitrary code, steal sensitive patient or research data, disrupt critical healthcare services, or pivot within networks for broader attacks. Given the criticality of healthcare infrastructure in Europe, successful exploitation could undermine patient safety, violate data protection regulations such as GDPR, and cause significant operational disruptions. The vulnerability’s remote exploitability without authentication or user interaction increases the attack surface, potentially enabling widespread automated attacks once exploit code is available. Additionally, compromised systems may serve as footholds for ransomware or espionage campaigns targeting European biomedical sectors. The impact extends beyond individual organizations to national healthcare resilience and research integrity, making timely mitigation essential.

European organizations should implement immediate mitigations including: 1) Monitoring and filtering incoming MFER files to detect and block suspicious or malformed inputs, especially those containing tag 133 (0x85). 2) Applying strict input validation and sandboxing parsing operations to isolate libbiosig processes and limit damage from potential exploits. 3) Coordinating with The Biosig Project to obtain and deploy patches as soon as they are released. 4) Conducting thorough code audits and fuzz testing of MFER parsing routines to identify and remediate similar vulnerabilities proactively. 5) Employing network segmentation to restrict access to systems processing MFER files, reducing exposure. 6) Enhancing endpoint detection and response capabilities to identify anomalous behaviors indicative of exploitation attempts. 7) Training staff to recognize and report suspicious files or activities related to biomedical data processing. These steps go beyond generic advice by focusing on the specific attack vector and operational context of libbiosig usage.