The vulnerability CVE-2025-54487 is a stack-based buffer overflow in the Biosig Project's libbiosig library, specifically in the MFER file parsing code. The issue occurs in biosig.c at line 8842 when processing tag 12 (0x0C), which relates to sampling resolution data. The code reads a length value 'len' from the MFER file and then attempts to read 'len-2' bytes into a fixed-size buffer without proper bounds checking. If 'len' exceeds 130, the buffer overflow occurs due to writing beyond the buffer's allocated size. Conversely, if 'len' is less than 2, an integer underflow causes 'len-2' to become a large unsigned integer, also leading to a buffer overflow. This improper validation allows an attacker to craft malicious MFER files that, when parsed by libbiosig, can overwrite the stack and potentially execute arbitrary code. The vulnerability requires no authentication or user interaction and can be triggered remotely by supplying a malicious file. The CVSS 3.1 score of 9.8 reflects the high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. The Biosig Project is used in biosignal processing, often in medical and research contexts, making this vulnerability particularly concerning for sensitive environments. No patches are currently linked, and no exploits are known in the wild, but the critical nature demands proactive mitigation.

For European organizations, the impact of CVE-2025-54487 is significant, especially in sectors relying on biosignal processing such as healthcare providers, medical device manufacturers, and research institutions. Exploitation could lead to arbitrary code execution, allowing attackers to compromise sensitive patient data, disrupt medical device functionality, or manipulate research data integrity. This could result in severe privacy violations, operational downtime, and potential harm to patients if medical devices are affected. The vulnerability’s remote and unauthenticated nature increases the risk of widespread exploitation. Given Europe's stringent data protection regulations like GDPR, breaches resulting from this vulnerability could also lead to substantial legal and financial penalties. Additionally, disruption in healthcare services could have broader societal impacts. Organizations using libbiosig in their software stacks must prioritize mitigation to prevent exploitation.

1. Monitor the Biosig Project for official patches addressing CVE-2025-54487 and apply them immediately upon release. 2. Until patches are available, implement strict input validation to reject MFER files with suspicious or out-of-range length values, especially those with 'len' less than 2 or greater than 130. 3. Employ sandboxing or isolated environments for processing MFER files to contain potential exploitation attempts. 4. Conduct code audits and static analysis on any custom integrations of libbiosig to identify and remediate similar unsafe parsing patterns. 5. Restrict file sources and enforce strict access controls to minimize exposure to malicious MFER files, particularly in networked or shared environments. 6. Increase monitoring and logging around systems processing biosignal data to detect anomalous behavior indicative of exploitation attempts. 7. Educate developers and security teams about the risks of unsafe buffer handling and the specifics of this vulnerability to improve future resilience.