CVE-2025-54481 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 8744 of biosig.c on the current master branch (35a819fa), when the Tag is 3:
else if (tag==3) {
// character code char v[17]; // [1]
if (len>16) fprintf(stderr,"Warning MFER tag2 incorrect length %i>16\n",len); curPos += ifread(&v,1,len,hdr); v[len] = 0;
In this case, the overflowed buffer is the newly-declared `v` \[1\] instead of `buf`. Since `v` is only 17 bytes large, much smaller values of `len` (even those encoded using a single octet) can trigger an overflow in this code path.
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Analysis
by VulDB Data Team • 09/02/2025
The vulnerability described in CVE-2025-54481 represents a critical stack-based buffer overflow within the MFER parsing component of the libbiosig library version 3.9.0 and master branch revision 35a819fa. This issue resides in the biosig.c source file at line 8744 within the tag processing logic, specifically when handling Tag value 3 which corresponds to character code data. The flaw occurs during the parsing of maliciously crafted MFER files that can be leveraged by attackers to execute arbitrary code remotely. The vulnerability is particularly concerning because it allows for code execution through a simple file upload or processing operation, making it highly exploitable in scenarios where users process untrusted medical file data.
The technical implementation of this vulnerability stems from inadequate bounds checking in the buffer management logic. The code declares a character buffer `v` with a fixed size of 17 bytes, but fails to properly validate the incoming length parameter `len` before copying data into this buffer. When Tag 3 is processed, the code executes `curPos += ifread(&v,1,len,hdr)` which reads `len` bytes into the 17-byte buffer `v`. The critical flaw occurs because the code only checks if `len > 16` and issues a warning, but does not prevent the actual buffer overflow when `len` exceeds the buffer capacity. The subsequent line `v[len] = 0` attempts to null-terminate the buffer, but when `len` is greater than 16, this operation writes beyond the allocated buffer boundaries, creating a classic stack overflow condition that can be exploited to overwrite adjacent stack memory.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete control over the affected application's execution flow. The stack-based buffer overflow creates opportunities for attackers to manipulate return addresses, function pointers, and other critical stack variables to redirect program execution. This vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows that occur in stack memory regions. From an adversarial perspective, this flaw maps directly to ATT&CK technique T1059.007 for command and script interpreter execution, as successful exploitation would allow attackers to execute arbitrary commands within the context of the vulnerable application. The vulnerability is particularly dangerous in medical environments where libbiosig is commonly used for processing electrocardiogram and other biomedical signal data, as it could enable attackers to compromise healthcare information systems.
Mitigation strategies for this vulnerability should include immediate patching of the libbiosig library to version 3.9.1 or later where the buffer overflow has been corrected. The fix should implement proper bounds checking to ensure that the length parameter never exceeds the buffer capacity, with explicit validation before any data copy operations. Additionally, users should implement input validation measures such as file format sanitization, length parameter validation, and sandboxing techniques to limit the potential impact of any remaining vulnerabilities. Organizations should also consider deploying intrusion detection systems to monitor for exploitation attempts and establish secure coding practices that emphasize buffer size validation and bounds checking. The vulnerability demonstrates the importance of proper input validation in security-critical applications and highlights the need for comprehensive code reviews focusing on memory management and buffer handling routines.