CVE-2025-54490 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 9090 of biosig.c on the current master branch (35a819fa), when the Tag is 64:
else if (tag==64) //0x40 {
// preamble char tmp[256]; // [1]
curPos += ifread(tmp,1,len,hdr);
In this case, the overflowed buffer is the newly-declared `tmp` \[1\] instead of `buf`. While `tmp` is larger than `buf`, having a size of 256 bytes, a stack overflow can still occur in cases where `len` is encoded using multiple octets and is greater than 256.
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability CVE-2025-54490 represents a critical stack-based buffer overflow in the libbiosig library version 3.9.0 and master branch revision 35a819fa, specifically within the MFER file parsing functionality. This issue stems from improper input validation during the processing of binary data structures, creating a pathway for remote code execution through crafted malicious files. The vulnerability manifests when the parser encounters a specific tag value of 64, which triggers a code path where a temporary buffer named tmp is allocated on the stack with a fixed size of 256 bytes. This flaw operates under the CWE-121 stack-based buffer overflow category, where the stack buffer size is insufficient to handle potentially large input data. The technical implementation involves the ifread function reading data into the tmp buffer without adequate bounds checking, particularly when the length parameter (len) exceeds the buffer capacity. The vulnerability operates at line 9090 in biosig.c where the tag value 64 is processed, making this a targeted attack vector that requires no special privileges to exploit. The specific condition occurs when the len parameter is encoded using multiple octets and surpasses the 256-byte limit of the tmp buffer, creating a scenario where memory corruption can occur beyond the intended buffer boundaries.
The operational impact of this vulnerability extends beyond simple memory corruption, presenting a severe security risk that can be leveraged for arbitrary code execution. Attackers can craft malicious MFER files that, when processed by applications using libbiosig, will trigger the buffer overflow condition and potentially allow remote code execution. This represents a classic attack pattern that aligns with the ATT&CK framework's T1203 - Exploitation for Client Execution and T1059 - Command and Scripting Interpreter, as the vulnerability enables attackers to execute arbitrary commands on affected systems. The exploitation process requires the attacker to create a specially crafted MFER file that encodes the len parameter in multiple octets to exceed the 256-byte tmp buffer capacity. The vulnerability's exploitability is enhanced by the fact that it occurs during normal file parsing operations, making it difficult to detect and prevent through standard network monitoring. The affected applications that utilize libbiosig for medical file processing become potential attack vectors, particularly in environments where untrusted file processing occurs. This vulnerability demonstrates a fundamental flaw in input validation and memory management practices, where the security model assumes that input lengths will not exceed predefined buffer sizes.
Mitigation strategies for CVE-2025-54490 should focus on immediate patching of the libbiosig library to version 3.9.1 or later, which contains the necessary fixes for the buffer overflow condition. Organizations should implement defensive programming practices including bounds checking on all input parameters, particularly when dealing with variable-length data fields in binary formats. The fix should involve replacing the fixed-size tmp buffer with dynamic allocation or ensuring that the len parameter is properly validated against the buffer size before any data is read. Additionally, applications using libbiosig should implement input sanitization and validation mechanisms to prevent malformed MFER files from reaching the vulnerable parsing code. System administrators should consider implementing application whitelisting and file type validation to prevent execution of untrusted files, while network segmentation and monitoring should be employed to detect potential exploitation attempts. The vulnerability highlights the importance of rigorous code review processes and static analysis tools to identify similar buffer overflow patterns in other parts of the codebase. Regular security updates and vulnerability assessments should be conducted to maintain protection against similar issues in medical data processing libraries, as the healthcare industry often relies on such specialized formats for critical data exchange. This vulnerability underscores the need for secure coding practices and adherence to memory safety principles in all software development processes, particularly in security-sensitive applications handling medical data.