CVE-2025-54480 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 arises in the MFER (Medical Format for Electroencephalographic Recordings) parsing functionality within biosig.c, notably at line 8719. When parsing a specially crafted MFER file, if the tag value is zero, the code does not properly validate the length of the data segment before reading it into a fixed-size buffer on the stack. This improper length check allows an attacker to overflow the buffer by providing a maliciously crafted MFER file with an incorrect length value. The overflow can overwrite adjacent memory on the stack, potentially leading to arbitrary code execution without requiring any privileges or user interaction. The CVSS v3.1 score of 9.8 reflects the critical nature of this vulnerability, indicating network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. Although no known exploits are currently reported in the wild, the vulnerability's characteristics make it a prime target for exploitation once a public exploit becomes available. The vulnerability is rooted in CWE-121, a classic stack-based buffer overflow, which is a well-understood and highly dangerous class of vulnerabilities. The absence of a patch link suggests that no official fix has been released yet, increasing the urgency for mitigation and monitoring.

For European organizations, the impact of this vulnerability can be severe, especially for those in the healthcare sector or research institutions that utilize The Biosig Project's libbiosig library for processing biomedical signal data such as EEG recordings. Exploitation could lead to arbitrary code execution on systems processing malicious MFER files, potentially allowing attackers to execute ransomware, steal sensitive medical data, or disrupt critical healthcare services. Given the critical CVSS score, successful exploitation could compromise confidentiality, integrity, and availability of affected systems. The vulnerability's network attack vector means that attackers can exploit it remotely by delivering malicious files, increasing the risk of widespread attacks. The lack of required privileges or user interaction further exacerbates the threat, making automated attacks feasible. European healthcare providers, universities, and research labs that handle biomedical signal data are at particular risk, potentially affecting patient privacy and safety. Additionally, organizations relying on libbiosig in embedded or industrial medical devices could face operational disruptions or safety hazards. The vulnerability could also be leveraged as an initial foothold in targeted attacks against high-value European targets, including government and critical infrastructure entities involved in health data processing.

Immediate mitigation steps include auditing all systems and applications that use libbiosig version 3.9.0 or the affected master branch for processing MFER files. Organizations should implement strict input validation and sandboxing around MFER file parsing to contain potential exploitation. Network-level controls such as blocking or filtering untrusted MFER file transfers and scanning incoming files for anomalies can reduce exposure. Employing application whitelisting and runtime protections like stack canaries, ASLR, and DEP can help mitigate exploitation impact. Since no official patch is currently available, organizations should monitor The Biosig Project repositories and security advisories closely for updates or patches. Where feasible, temporarily disabling or restricting the use of libbiosig for MFER parsing until a patch is released is advisable. Incident response teams should prepare to detect exploitation attempts by monitoring for unusual process behaviors or crashes related to biosig.c. Finally, organizations should educate developers and users about the risks of processing untrusted biomedical data files and enforce strict file provenance verification.