CVE-2025-54494 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 9205 of biosig.c on the current master branch (35a819fa), when the Tag is 133:
else if (tag==133) //0x85 {
curPos += ifread(buf,1,len,hdr);
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability identified as CVE-2025-54494 represents a critical stack-based buffer overflow within the MFER file parsing component of the libbiosig library version 3.9.0 and subsequent master branch commits. This flaw resides in the biosig.c source file at line 9205 within the handling logic for Tag value 133, which corresponds to hexadecimal 0x85. The vulnerability stems from insufficient input validation when processing maliciously crafted MFER files that contain oversized data structures for this specific tag identifier. The buffer overflow occurs during the execution of the ifread function call where data is read into a buffer without proper bounds checking, allowing an attacker to overwrite adjacent stack memory locations.
The technical exploitation of this vulnerability leverages the improper handling of the len parameter within the Tag 133 processing branch. When the parser encounters a malformed MFER file containing a Tag 133 structure with an oversized length field, the curPos variable accumulates the result of ifread operations without validating that the buffer allocation can accommodate the specified data length. This creates a scenario where attacker-controlled data can overflow the allocated stack buffer, potentially corrupting return addresses, function pointers, and other critical stack variables. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions where the buffer size is insufficient to contain the data being written.
From an operational perspective, this vulnerability presents a significant risk to systems that process medical file formats using the libbiosig library, particularly in healthcare environments where electronic medical records are parsed and analyzed. Attackers can craft malicious MFER files that, when processed by vulnerable applications, will trigger the buffer overflow condition and potentially execute arbitrary code with the privileges of the affected process. The attack vector is straightforward requiring only the delivery of a malicious file to the target system, making this vulnerability particularly dangerous in automated processing environments. This aligns with ATT&CK technique T1204.002, where adversaries leverage malicious files to execute code on compromised systems.
The impact extends beyond immediate code execution to potential system compromise and data breach scenarios. Successful exploitation could allow attackers to install persistent backdoors, escalate privileges, or access sensitive medical data stored within the affected systems. The vulnerability affects not only the direct users of the libbiosig library but also any applications that depend on it for medical file processing, including electronic health record systems, medical imaging software, and research data analysis platforms. Organizations should implement immediate mitigations including updating to patched versions of libbiosig, implementing file validation controls, and restricting processing of untrusted MFER files. The vulnerability demonstrates the importance of robust input validation and memory safety practices in security-critical medical software environments where data integrity and system reliability are paramount.