External risk intelligence

Libbiosig MFER Parsing Stack Buffer Overflow Vulnerabilities

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2025-66048

libbiosig is a specialized software library used for processing biomedical signal data files. It is typically integrated into offline research, clinical, or data analysis applications rather than functioning as an internet-facing service, web application, or edge gateway. Exposure depends on the user processing an untrusted file within a local application, which does not constitute a public-facing network surface.

Out-of-bounds Write

Libbiosig Project Libbiosig

before 3.9.2

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in the Biosig Project's library, specifically within its MFER file parsing. This flaw could allow for arbitrary code execution if an attacker can trick a user into opening a specially crafted malicious file, potentially impacting systems that process biomedical signal data. The main concern is confirming relevance and exposure.

Flaw lets malicious files run code.
Matters for data analysis software.
Confirm if your systems use this library.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by crafting a malicious MFER file. If a user or an application processes this file, it could lead to a stack-based buffer overflow, potentially allowing the attacker to execute arbitrary code. The vulnerability is triggered when a specific tag (133) is encountered within the MFER file.

No user interaction required for attack.
Malicious MFER file processing.
Arbitrary code execution risk.

Live Threat

Current exploitation, exposure, and threat context

Stack-based buffer overflow vulnerabilities in MFER parsing could allow arbitrary code execution when a specially crafted MFER file, with a Tag of 133, is processed. This could impact systems that handle biomedical signal data files.

System integrity and code execution.
Processing a malicious MFER file.
Unauthorized code execution on the system.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Biosig Project libbiosig library's MFER parsing functionality is impacted by stack-based buffer overflow vulnerabilities, which could allow for arbitrary code execution if a specially crafted MFER file is processed. This issue likely falls under the responsibility of application owners or development teams integrating the libbiosig library. The immediate first step is to identify all instances where libbiosig is used, confirm the criticality of these applications, and determine the accountable owner to plan for remediation.

Application owners should manage this issue.
Verify all libbiosig integrations.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is libbiosig?

libbiosig is a software library developed by The Biosig Project. It is primarily used by researchers and clinicians to read, write, and analyze biomedical signal data, such as EEG or ECG recordings. Because it handles various file formats, it is often embedded within specialized data analysis applications rather than running as a standalone program.

What does CVE-2025-66048 mean?

CVE-2025-66048 identifies a security weakness known as a stack-based buffer overflow, categorized under CWE-121 and CWE-787. This happens when the software tries to store more data in a specific memory area than it can hold. In this case, when the library parses MFER files, the overflow can allow an attacker to gain control and execute arbitrary code on the host system.

How is this vulnerability triggered?

The vulnerability is triggered when the library processes a specially crafted MFER file containing a specific data structure, specifically when Tag 133 is encountered. Processing legitimate files that do not contain this specific malicious tag sequence does not trigger the flaw. The risk occurs only when the library attempts to parse a file intentionally designed to exploit this memory handling error.

Is my system at risk?

According to Halo Surface Signal, this risk is very unlikely for public-facing infrastructure. libbiosig is typically used in offline research or local clinical analysis tools rather than internet-facing services or web gateways. You are primarily at risk if you use applications that process untrusted or externally sourced biomedical signal files, rather than data coming from your own trusted laboratory instruments.

What should I do if I use libbiosig?

Your first step is to perform an inventory of your software environment to identify any applications that integrate libbiosig versions earlier than 3.9.2. Once identified, coordinate with your development or application support teams to assess how these tools handle incoming files and prioritize updating the library to a patched version to resolve the underlying memory safety issues.

References

talosintelligence.com/vulnerability_reports/TALOS-2025-2296

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.