CVE-2025-54485 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 8785 of biosig.c on the current master branch (35a819fa), when the Tag is 8:
else if (tag==8) {
if (len>2) fprintf(stderr,"Warning MFER tag8 incorrect length %i>2\n",len); curPos += ifread(buf,1,len,hdr);
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Analysis
by VulDB Data Team • 09/02/2025
The CVE-2025-54485 vulnerability represents a critical stack-based buffer overflow within the MFER parsing component of the libbiosig library version 3.9.0 and its master branch implementation. This security flaw resides in the biosig.c source file at line 8785, specifically within the handling logic for MFER tag 8 processing. The vulnerability stems from insufficient input validation and bounds checking during the parsing of structured binary data formats, creating an exploitable condition that can be triggered through manipulation of the input file structure. The affected library is widely used in biomedical signal processing applications for reading and writing physiological data, making this vulnerability particularly concerning for systems handling sensitive medical information. The flaw manifests when the system encounters an MFER file containing a malformed tag 8 structure, where the length parameter exceeds predetermined limits without proper boundary verification. This particular code path operates within the broader context of medical file format parsing, where the software must handle various data structures while maintaining memory safety and data integrity. The vulnerability's exploitation potential is significantly enhanced by the fact that it occurs during file parsing operations, which typically execute with elevated privileges when processing user-provided data. The specific implementation issue involves the ifread function call where data is read into a buffer without adequate size validation against the len parameter, creating a classic buffer overflow scenario. The error handling logic for tag 8 specifically issues a warning message when length exceeds two bytes but fails to prevent the actual buffer overflow condition from occurring. This vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which describes buffer overflow conditions where insufficient bounds checking allows data to overwrite adjacent stack memory. The attack vector is particularly dangerous because it can be executed through simple file manipulation without requiring complex network access or specialized equipment. The vulnerability demonstrates poor input sanitization practices and highlights the importance of proper defensive programming techniques in security-critical applications. When exploited, this vulnerability allows an attacker to execute arbitrary code with the privileges of the affected application, potentially leading to complete system compromise. The impact extends beyond local privilege escalation to include potential data exfiltration, system persistence mechanisms, and further lateral movement within networked environments. The ATT&CK framework categorizes this vulnerability under T1059.007 Command and Scripting Interpreter: PowerShell and T1203 Exploitation for Client Execution, as it enables attackers to execute malicious code through legitimate file processing mechanisms. The vulnerability's presence in both the stable release and development branch indicates a persistent issue that requires immediate attention and patching across all affected systems. The lack of proper input validation in this parsing routine represents a fundamental security weakness that could be exploited in various attack scenarios including remote code execution, privilege escalation, and denial of service conditions.
The technical implementation of this vulnerability demonstrates a classic buffer overflow condition where the len parameter controls how much data is read into a fixed-size buffer. The code path specifically processes MFER tag 8 structures and fails to validate that the length parameter remains within safe bounds before performing the ifread operation. This oversight creates a scenario where an attacker can craft an MFER file with an oversized len value that exceeds the allocated buffer space, causing adjacent memory to be overwritten. The warning message issued when len exceeds two bytes is purely informational and does not prevent the buffer overflow from occurring, indicating a flawed security design approach. The vulnerability affects the broader biosig library ecosystem and could potentially impact numerous applications that rely on this library for processing medical data files. The stack-based nature of the overflow means that attackers can overwrite return addresses, function pointers, and other critical stack memory locations to redirect program execution flow. The specific line of code where the vulnerability occurs demonstrates a lack of proper bounds checking that should have been implemented as part of standard defensive programming practices. This flaw represents a failure in input validation and memory management that directly violates security best practices. The vulnerability's exploitation requires only the ability to create or modify MFER files, making it particularly dangerous as it can be triggered through simple file manipulation without requiring network access or complex attack chains. The affected environment includes any system that processes MFER files through the libbiosig library, which encompasses various medical data processing applications, research systems, and healthcare information technology infrastructure. The security implications extend to potential data integrity compromises, where attackers could modify or corrupt medical records during processing operations. The vulnerability's presence in the master branch indicates that this is not a temporary issue but rather a persistent design flaw that requires comprehensive code review and remediation across the entire codebase. The combination of the buffer overflow and the ability to execute arbitrary code through file processing creates a severe threat vector that could be leveraged for advanced persistent threat campaigns targeting healthcare and research institutions. Proper mitigation requires immediate patching of the affected library versions and implementation of input validation controls that prevent oversized data from being processed through the vulnerable parsing functions.
Mitigation strategies for CVE-2025-54485 should prioritize immediate patching of all affected libbiosig installations to version 3.9.1 or later, which contains the necessary fixes for the buffer overflow condition. Organizations should implement strict input validation policies that prevent processing of untrusted MFER files, particularly those that may contain malformed tag structures. The recommended approach includes deploying file format validation controls that check for proper length parameters before allowing data processing to proceed. Security monitoring should be enhanced to detect suspicious file processing activities and potential exploitation attempts through unusual data patterns. Network segmentation and privilege separation should be implemented to limit the impact of successful exploitation attempts, ensuring that even if an attacker gains code execution capabilities, they cannot easily escalate privileges or access sensitive systems. The vulnerability's exploitation requires minimal user interaction, making it particularly dangerous in environments where users may process untrusted medical data files from external sources. Regular security audits should be conducted to identify other potential buffer overflow conditions within the same codebase or similar libraries. The implementation of address space layout randomization, stack canaries, and other exploit mitigation techniques should be considered as additional protective measures. System administrators should also monitor for unusual file processing patterns and implement automated scanning for potentially malicious MFER files that could exploit this vulnerability. The fix for this vulnerability should include comprehensive bounds checking that validates the len parameter against maximum buffer sizes before any data is read into memory. The security controls should also include runtime protections that can detect and prevent buffer overflow conditions during execution. Organizations should maintain updated threat intelligence feeds to stay informed about potential exploitation attempts targeting this specific vulnerability. Regular security training for personnel handling medical data should include awareness of file format vulnerabilities and safe processing practices. The vulnerability's impact on medical data processing systems makes it particularly critical for healthcare organizations to implement immediate protective measures while awaiting official patches. The remediation process should include thorough testing of patched libraries to ensure that the fix does not introduce regressions in legitimate file processing functionality. Proper logging and incident response procedures should be established to quickly identify and respond to potential exploitation attempts. The vulnerability's classification as a high-severity issue necessitates immediate action across all affected systems, with priority given to critical infrastructure and medical data processing environments.