CVE-2025-54489: Critical Stack-based Buffer Overflow Vulnerability in Biosig Project libbiosig 3.9.0

Overview

In the realm of cybersecurity, a new critical vulnerability has been identified in the Biosig Project libbiosig 3.9.0 and its Master Branch. The vulnerability, tagged as “CVE-2025-54489,” is a stack-based buffer overflow vulnerability that could potentially lead to arbitrary code execution if a specially crafted MFER file is provided by an attacker. The vulnerability is of high concern due to its impact on the integrity, confidentiality, and availability of the affected systems, making it a high-priority issue for any organization using the affected product.

Vulnerability Summary

CVE ID: CVE-2025-54489
Severity: Critical (CVSS 9.8)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: Potential system compromise, arbitrary code execution or data leakage

Affected Products

Product | Affected Versions

Biosig Project libbiosig | 3.9.0 and Master Branch (35a819fa)

How the Exploit Works

The exploit leverages a stack-based buffer overflow vulnerability that exists in the MFER parsing functionality of the Biosig Project libbiosig. This vulnerability manifests when the Tag is 63. The number of bytes read is not the Data Length decoded from the current frame in the file (`len`) but rather is a new length contained in a single octet read from the same input file (`len2`). A stack-based buffer overflow condition can occur despite this as the destination buffer is `buf`, which has a size of only 128 bytes, while `len2` can be as large as 255.

Conceptual Example Code

Here is a conceptual example in pseudocode of how the vulnerability might be exploited:

# Assuming the attacker has control over the MFER file provided
mfer_file = open('malicious.mfer', 'w')
tag = 63
len = 128  # not exceeding buf size
tag2 = 0
len2 = 255  # exceeding buf size
# Write these values to the MFER file
mfer_file.write(tag)
mfer_file.write(len)
mfer_file.write(tag2)
mfer_file.write(len2)
# Fill with arbitrary data to cause buffer overflow
for _ in range(len2):
mfer_file.write('A')
mfer_file.close()

In this example, the attacker crafts an MFER file that when parsed, causes a buffer overflow due to the mismatch between `len` and `len2` values. This could potentially allow an attacker to execute arbitrary code on the affected system.

Mitigation Guidance

All users are strongly recommended to apply the vendor’s patch to mitigate the risk of this vulnerability. In the interim, organizations can employ a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to detect and possibly block attempts to exploit this vulnerability.