CVE-2025-53853 is a critical heap-based buffer overflow vulnerability identified in the ISHNE parsing functionality of The Biosig Project's libbiosig library, specifically affecting versions 3.9.0 and the Master Branch commit 35a819fa. Libbiosig is an open-source library used for biosignal processing, including electrocardiogram (ECG) data handling. The vulnerability arises when the library processes specially crafted ISHNE ECG annotation files. Due to improper bounds checking during parsing, an attacker can cause a heap buffer overflow, which can lead to arbitrary code execution without requiring any user interaction or privileges. The CVSS v3.1 score of 9.8 reflects the high severity, with network attack vector, low attack complexity, no privileges required, and no user interaction needed. Exploitation could allow remote attackers to execute malicious code on systems that automatically parse or process untrusted ISHNE ECG annotation files using the vulnerable libbiosig versions. Although no known exploits are currently reported in the wild, the vulnerability's nature and severity make it a significant risk, especially in medical and research environments where biosignal data processing is common. The absence of available patches at the time of publication increases the urgency for mitigation and monitoring.

For European organizations, especially those in healthcare, biomedical research, and medical device manufacturing, this vulnerability poses a substantial risk. Many European hospitals and research institutions utilize biosignal processing tools that may incorporate libbiosig for ECG data analysis. Successful exploitation could lead to full system compromise, data breaches involving sensitive patient information, disruption of critical medical data processing, and potential manipulation of medical records. The confidentiality, integrity, and availability of patient data and medical systems could be severely impacted. Given the criticality of healthcare infrastructure in Europe and strict regulatory frameworks like GDPR, exploitation could also result in significant legal and financial consequences. Additionally, organizations involved in medical device development or clinical trials could face operational disruptions and reputational damage if their systems are compromised through this vulnerability.

Immediate mitigation steps include auditing all systems and applications that utilize libbiosig for ECG data processing to identify affected versions (3.9.0 and Master Branch 35a819fa). Until an official patch is released, organizations should implement strict input validation and sandboxing for any ISHNE ECG annotation files, especially those received from untrusted or external sources. Network-level controls such as intrusion detection/prevention systems (IDS/IPS) should be tuned to detect anomalous ISHNE file traffic. Employ application whitelisting and restrict execution privileges of processes handling biosignal data to minimize potential impact. Organizations should also monitor security advisories from The Biosig Project and related communities for patches or updates. In parallel, conducting threat hunting for any signs of exploitation attempts and enhancing endpoint detection and response (EDR) capabilities focused on memory corruption indicators will help in early detection. Finally, educating staff about the risks of processing untrusted biosignal files and enforcing strict file handling policies will reduce exposure.