CVE-2025-54492 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 9141 of biosig.c on the current master branch (35a819fa), when the Tag is 67:
else if (tag==67) //0x43: Sample skew {
int skew=0; // [1]
curPos += ifread(&skew, 1, len,hdr);
In this case, the address of the newly-defined integer `skew` \[1\] is overflowed instead of `buf`. This means a stack overflow can occur using much smaller values of `len` in this code path.
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability described in CVE-2025-54492 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 flaw resides in the biosig.c source file at line 9141, specifically within the handling logic for Tag value 67, which corresponds to the Sample skew parameter in medical file formats. The vulnerability stems from improper bounds checking during the parsing of structured data elements, creating a scenario where attacker-controlled input can overwrite adjacent stack memory locations. The flaw demonstrates characteristics consistent with CWE-121 Stack-based Buffer Overflow, where insufficient validation allows data to exceed the allocated buffer boundaries.
The technical implementation of this vulnerability occurs when processing MFER files containing maliciously crafted data structures. During the parsing of Tag 67, the code attempts to read a skew value using the ifread function, but fails to properly validate the length parameter len before performing the read operation. The integer variable skew is allocated on the stack at line 9141, and when the length parameter exceeds the expected bounds, the read operation overflows the stack allocation intended for skew. This misconfiguration allows attackers to control the amount of data written beyond the legitimate buffer boundaries, effectively corrupting the stack frame. The vulnerability operates under the ATT&CK technique T1203 Exploitation for Client Execution, as it enables arbitrary code execution through manipulation of file inputs.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides a pathway for complete system compromise. An attacker who can convince a victim to process a maliciously crafted MFER file can achieve arbitrary code execution with the privileges of the executing process. This could result in unauthorized data access, system takeover, or further lateral movement within a network environment. The vulnerability is particularly concerning because it can be triggered through normal file processing operations, making it difficult to detect and prevent. The relatively small values of len required to trigger the overflow make this vulnerability accessible even with limited knowledge of the specific attack parameters, increasing the probability of successful exploitation. The stack-based nature of the overflow means that critical return addresses and function parameters can be overwritten, potentially allowing attackers to redirect program execution flow.
Mitigation strategies for CVE-2025-54492 should prioritize immediate patching of affected libbiosig versions, with the implementation of comprehensive input validation and bounds checking throughout the MFER parsing functionality. Developers should implement strict validation of the len parameter before any read operations occur, ensuring that all data transfers remain within allocated buffer boundaries. Memory safety practices including stack canary implementation and compiler-based protections such as stack smashing protection should be enabled. Additionally, input sanitization techniques should be employed to filter out potentially malicious file structures before they reach the vulnerable parsing code paths. Organizations should also consider implementing file type validation and sandboxed processing environments for handling medical file formats to reduce the attack surface. The vulnerability highlights the importance of maintaining up-to-date security practices and conducting regular code reviews focused on memory safety, particularly in libraries that process untrusted data from external sources.