CVE-2025-54490 is a stack-based buffer overflow vulnerability identified in The Biosig Project's libbiosig library, specifically in the MFER file parsing code. The vulnerability arises in the function handling tag 64 (0x40) where a local buffer 'tmp' of 256 bytes is allocated on the stack. The code reads 'len' bytes from the input file into this buffer without adequately verifying that 'len' does not exceed 256. Since 'len' can be encoded using multiple octets, an attacker can craft an MFER file with a length field larger than 256, causing a buffer overflow on the stack. This overflow can overwrite adjacent stack data, including return addresses, enabling arbitrary code execution. The vulnerability affects libbiosig version 3.9.0 and the current master branch (commit 35a819fa). The CVSS 3.1 base score is 9.8, indicating critical severity with network attack vector, low attack complexity, no privileges or user interaction required, and full impact on confidentiality, integrity, and availability. No public exploits are known yet, but the vulnerability is straightforward to exploit by delivering a malicious MFER file to a system processing biosignal data with libbiosig. This poses a significant risk to applications relying on libbiosig for biosignal analysis, including medical devices, research tools, and healthcare software. The vulnerability's root cause is improper input validation and unsafe buffer handling in biosig.c at line 9090. Without patches currently available, organizations must implement compensating controls to mitigate risk.

The impact of CVE-2025-54490 on European organizations is substantial, particularly for those in healthcare, biomedical research, and related industries that utilize biosignal processing software incorporating libbiosig. Successful exploitation can lead to arbitrary code execution, allowing attackers to compromise system confidentiality, integrity, and availability. This could result in unauthorized access to sensitive patient data, manipulation or disruption of medical device functionality, and potential safety risks to patients. Additionally, compromised research environments could lead to data tampering or intellectual property theft. The vulnerability's network attack vector and lack of required privileges mean attackers can exploit it remotely by delivering malicious MFER files, increasing the threat surface. Given the criticality of healthcare infrastructure in Europe and stringent data protection regulations like GDPR, the consequences of exploitation include regulatory penalties, reputational damage, and operational disruptions. The absence of known exploits currently provides a window for proactive mitigation, but the ease of exploitation and critical severity necessitate urgent action to prevent potential attacks.

1. Monitor The Biosig Project repositories and security advisories closely for official patches addressing CVE-2025-54490 and apply them promptly once released. 2. Until patches are available, implement strict input validation on MFER files before processing, including enforcing maximum length constraints on fields to prevent buffer overflows. 3. Employ runtime protections such as stack canaries, Address Space Layout Randomization (ASLR), and Data Execution Prevention (DEP) on systems running libbiosig to mitigate exploitation impact. 4. Restrict access to systems processing MFER files by limiting network exposure and applying strict access controls to reduce the attack surface. 5. Conduct code audits and static analysis on custom integrations of libbiosig to identify and remediate unsafe buffer handling. 6. Deploy intrusion detection systems capable of detecting anomalous MFER file inputs or exploitation attempts. 7. Educate developers and system administrators about the vulnerability to ensure awareness and prompt response. 8. Consider sandboxing or isolating biosignal processing components to contain potential exploitation effects. 9. Maintain comprehensive backups and incident response plans tailored to potential exploitation scenarios involving biosignal processing systems.