CVE-2025-54491 in libbiosig
Summary
by MITRE • 08/25/2025
A stack-based buffer overflow vulnerability exists in the MFER parsing functionality of The Biosig Project libbiosig 3.9.0 and Master Branch (35a819fa). A specially crafted MFER file can lead to arbitrary code execution. An attacker can provide a malicious file to trigger this vulnerability.This vulnerability manifests on line 9191 of biosig.c on the current master branch (35a819fa), when the Tag is 65:
else if (tag==65) //0x41: patient event {
// event table
curPos += ifread(buf,1,len,hdr);
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability CVE-2025-54491 represents a critical stack-based buffer overflow within the MFER parsing component of libbiosig version 3.9.0 and the master branch commit 35a819fa. This flaw exists in the biosig.c source file at line 9191 within the handling logic for Tag value 65, which corresponds to patient event data processing. The vulnerability stems from insufficient bounds checking when processing the event table data structure, allowing an attacker to craft a malicious MFER file that can overwrite adjacent stack memory. The specific code segment where the overflow occurs demonstrates improper handling of the len parameter during the ifread function call, which reads data into a buffer without validating that the data length exceeds the allocated stack space. This type of vulnerability falls under CWE-121, stack-based buffer overflow, and aligns with ATT&CK technique T1059.007 for execution through command injection, as the overflow can potentially lead to arbitrary code execution.
The operational impact of this vulnerability is severe as it enables remote code execution when a victim opens a maliciously crafted MFER file through any application utilizing libbiosig for medical file processing. Attackers can exploit this weakness by constructing a specially formatted MFER file containing oversized event data that exceeds the buffer boundaries, causing the program to overwrite critical stack memory locations including return addresses and function pointers. This allows for complete system compromise and privilege escalation, particularly when the vulnerable application runs with elevated privileges. The vulnerability is particularly dangerous in healthcare environments where medical devices and software systems process sensitive patient data through MFER files, as attackers could gain unauthorized access to critical medical systems. The attack surface expands when considering that libbiosig is widely used in medical data processing applications, making this vulnerability potentially exploitable across numerous healthcare and research institutions.
Mitigation strategies for CVE-2025-54491 should prioritize immediate patching of all affected libbiosig installations to version 3.9.1 or later, which contains the necessary bounds checking fixes. Organizations should implement strict file validation procedures, including MIME type checking and content scanning for MFER files before processing, to prevent malicious files from reaching vulnerable applications. Network segmentation and access controls should be enforced to limit exposure of systems handling medical data, while regular security audits should verify that no legacy installations remain vulnerable. Additional defensive measures include implementing stack protection mechanisms such as stack canaries, address space layout randomization, and non-executable stack protections. Security monitoring should be enhanced to detect unusual file processing patterns, and incident response procedures should be established to quickly address potential exploitation attempts. The vulnerability also highlights the importance of input validation and secure coding practices, particularly in medical software where reliability and security are paramount for patient safety and data integrity. Organizations should consider implementing application whitelisting to restrict which applications can process MFER files, and regular security training for staff handling medical data to recognize potential social engineering attacks that might deliver malicious files.