CVE-2025-54480 is a stack-based buffer overflow vulnerability identified in The Biosig Project's libbiosig library, specifically affecting version 3.9.0 and the current master branch (commit 35a819fa). The vulnerability resides in the MFER file parsing code, particularly when processing a tag value of 0. The code fails to properly validate the length of the data associated with this tag, as seen in the snippet where if the tag equals 0 and the length is not 1, a warning is issued but the function proceeds to read data into a buffer without adequate bounds checking. This improper handling allows an attacker to craft a malicious MFER file that triggers a buffer overflow on the stack, potentially overwriting return addresses or other control data. This can lead to arbitrary code execution under the privileges of the process using libbiosig. The vulnerability is remotely exploitable as it requires only a malicious file input, with no authentication or user interaction needed. The CVSS v3.1 score of 9.8 reflects the critical nature of this flaw, with network attack vector, low attack complexity, no privileges required, and no user interaction. The impact covers confidentiality, integrity, and availability, making it a severe threat. Although no public exploits are reported yet, the vulnerability's characteristics suggest it could be weaponized quickly. Libbiosig is used primarily in biomedical signal processing applications, including EEG and ECG data analysis, which are critical in healthcare and research environments. The vulnerability's presence in such sensitive contexts raises concerns about patient data confidentiality and system reliability.

For European organizations, especially those in healthcare, biomedical research, and biometric authentication sectors, this vulnerability poses a significant risk. Exploitation could lead to unauthorized code execution, potentially compromising sensitive patient data, disrupting medical device operations, or corrupting research data integrity. The critical severity means attackers could gain control over affected systems remotely, leading to data breaches, denial of service, or further lateral movement within networks. Given the reliance on libbiosig in medical signal processing, compromised systems could impact patient care and safety. Additionally, organizations involved in biometric authentication could face identity theft or fraud. The disruption could also affect compliance with GDPR and other data protection regulations, exposing organizations to legal and financial penalties. The absence of known exploits currently provides a window for proactive mitigation, but the high CVSS score indicates urgent attention is required.

1. Immediate mitigation should focus on restricting the acceptance of untrusted MFER files, implementing strict input validation and sanitization at the application level before passing data to libbiosig. 2. Monitor for updates from The Biosig Project and apply patches as soon as they become available; maintain close communication with the vendor or open-source community for timely fixes. 3. Employ runtime protections such as stack canaries, ASLR, and DEP (Data Execution Prevention) to reduce exploitation success. 4. Conduct code audits and fuzz testing on the MFER parsing components to identify and remediate similar vulnerabilities proactively. 5. Isolate systems processing MFER files in segmented network zones to limit potential lateral movement if exploited. 6. Implement file integrity monitoring and anomaly detection to identify suspicious MFER files or unexpected application behavior. 7. Educate developers and security teams about secure coding practices related to buffer management and input validation, especially in biomedical software contexts. 8. For organizations deploying libbiosig in critical environments, consider temporary workarounds such as disabling MFER file support if feasible until patches are applied.