CVE-2025-53511 is a critical heap-based buffer overflow vulnerability identified in the MFER 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 parsing and handling various biosignal file formats such as MFER (Medical and Functional Electrocardiogram Recordings). The vulnerability arises when the library processes a specially crafted MFER file, which causes a heap buffer overflow due to improper bounds checking or memory management during parsing. This overflow can corrupt adjacent memory on the heap, potentially allowing an attacker to execute arbitrary code within the context of the vulnerable application. Notably, the vulnerability requires no authentication or user interaction beyond supplying the malicious MFER file to the application using libbiosig. The CVSS v3.1 score is 9.8 (critical), reflecting the vulnerability's network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and full impact on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no known exploits are currently reported in the wild, the severity and ease of exploitation make this a high-risk issue. The lack of available patches at the time of publication underscores the urgency for users to apply mitigations or monitor for updates. Given libbiosig's role in medical and research environments, exploitation could lead to unauthorized code execution, data compromise, or denial of service in systems processing biosignal data.

For European organizations, especially those in healthcare, biomedical research, and medical device manufacturing, this vulnerability poses a significant risk. Many European hospitals, research institutions, and medical device vendors utilize biosignal processing libraries like libbiosig for diagnostics, monitoring, and research purposes. Exploitation could lead to unauthorized access or control over critical medical data and systems, potentially impacting patient safety, data confidentiality, and system availability. The critical nature of the vulnerability means that attackers could execute arbitrary code remotely by simply providing a malicious MFER file, which could be delivered via network shares, email attachments, or compromised data repositories. This could facilitate ransomware attacks, data theft, or sabotage of medical research data. Additionally, regulatory frameworks such as the EU's GDPR and the Medical Device Regulation (MDR) impose strict requirements on data protection and device security, meaning exploitation could result in significant legal and financial consequences for affected organizations. The absence of known exploits currently provides a window for proactive defense, but the high severity demands immediate attention.

Given the absence of an official patch at the time of this report, European organizations should implement the following specific mitigations: 1) Restrict and monitor the ingestion of MFER files to trusted sources only, employing strict validation and sandboxing techniques to analyze files before processing. 2) Employ application-layer firewalls or intrusion prevention systems (IPS) capable of detecting anomalous or malformed MFER file traffic. 3) Isolate systems that process biosignal data using libbiosig from general network access to reduce exposure to untrusted inputs. 4) Implement strict access controls and logging around applications using libbiosig to detect suspicious activity promptly. 5) Engage with vendors or open-source maintainers to obtain patches or updates as soon as they become available and prioritize their deployment. 6) Conduct code audits or use static/dynamic analysis tools on custom implementations of libbiosig to identify and remediate unsafe parsing logic. 7) Educate staff in healthcare and research environments about the risks of opening untrusted biosignal files and enforce policies to prevent unauthorized file transfers. These targeted mitigations go beyond generic advice by focusing on controlling the attack vector (malicious MFER files) and hardening the processing environment.