CVE-2025-54489VulnerabilityPublished 25 Aug 2025Updated 3 Nov 2025

CVE-2025-54489: The Biosig Project libbiosig · Stack-based Buffer Overflow

Affects The Biosig Project libbiosigSource CVE Database V5

Not known to be exploited · CVSS 9.8 Critical.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

9.8Critical

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
The Biosig Project libbiosig	Affected =3.9.0	Fixed in–

AI-suggested

1. Monitor The Biosig Project's official channels for patches addressing CVE-2025-54489 and apply them promptly once released. 2. Until patches are available, implement strict input validation and sanitization on all MFER files before processing, including limiting the maximum allowed length fields to the buffer size or less. 3. Employ sandboxing or containerization techniques to isolate the libbiosig processing environment, minimizing potential damage from exploitation. 4. Use application-layer firewalls or intrusion detection systems to detect and block malformed or suspicious MFER files. 5. Conduct code audits and static analysis on any custom integrations of libbiosig to identify similar unsafe parsing patterns. 6. Educate staff on the risks of processing untrusted biosignal files and enforce policies restricting file sources. 7. Maintain up-to-date backups and incident response plans tailored to potential exploitation scenarios. 8. Consider deploying runtime protections such as stack canaries, address space layout randomization (ASLR), and control flow integrity (CFI) in applications using libbiosig to reduce exploitation success.

Description

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 8970 of biosig.c on the current master branch (35a819fa), when the Tag is 63: else if (tag==63) { uint8_t tag2=255, len2=255; count = 0; while ((count<len) && !(FlagInfiniteLength && len2==0 && tag2==0)){ curPos += ifread(&tag2,1,1,hdr); curPos += ifread(&len2,1,1,hdr); if (VERBOSE_LEVEL==9) fprintf(stdout,"MFER: tag=%3i chan=%2i len=%-4i tag2=%3i len2=%3i curPos=%i %li count=%4i\n",tag,chan,len,tag2,len2,curPos,iftell(hdr),(int)count); if (FlagInfiniteLength && len2==0 && tag2==0) break; count += (2+len2); curPos += ifread(&buf,1,len2,hdr); Here, 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`). Despite this, a stack-based buffer overflow condition can still occur, as the destination buffer is still `buf`, which has a size of only 128 bytes, while `len2` can be as large as 255.

Impact

The impact on European organizations is significant, especially those in healthcare, biomedical research, and clinical diagnostics that utilize The Biosig Project's libbiosig library for biosignal processing. Successful exploitation could lead to arbitrary code execution, allowing attackers to compromise system confidentiality by accessing sensitive patient data, integrity by altering biosignal data or analysis results, and availability by causing system crashes or denial of service. This could disrupt critical healthcare services, research activities, and patient monitoring systems. Additionally, compromised systems could be used as footholds for lateral movement within networks, increasing the risk of broader breaches. Given the criticality and ease of exploitation, organizations face a high risk of targeted attacks or automated exploitation attempts once proof-of-concept exploits become available. The lack of authentication and user interaction requirements further amplifies the threat, as malicious files could be delivered via network services or removable media without user awareness.

Summary

CVE-2025-54489 is a stack-based buffer overflow vulnerability identified in The Biosig Project's libbiosig library, specifically in versions 3.9.0 and the master branch (commit 35a819fa). The vulnerability resides in the MFER file parsing code, particularly when processing tag 63. The parsing logic reads a length value (len2) from the input file, which can be as large as 255 bytes, but copies data into a fixed-size buffer of only 128 bytes (buf). This discrepancy allows an attacker to overflow the stack buffer by providing a specially crafted MFER file with maliciously large len2 values. The overflow can overwrite the stack, enabling arbitrary code execution. The vulnerability is exploitable remotely without authentication or user interaction, as it only requires the victim to process a malicious MFER file. The CVSS v3.1 score is 9.8 (critical), reflecting the vulnerability's ease of exploitation (network vector, low attack complexity), and its impact on confidentiality, integrity, and availability. The root cause is improper bounds checking during the parsing loop, where the code increments counters and reads data without verifying that len2 does not exceed the buffer size. No patches were listed at the time of disclosure, but remediation would involve fixing the input validation and buffer size checks. This vulnerability is particularly concerning for applications relying on libbiosig for biosignal data processing, such as medical devices, research tools, and clinical software.

CWE-121Stack-based Buffer Overflow (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #14
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Implementation
Implement and perform bounds checking on input.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2025, 20:32 UTC

WeaknessesCWE-121

Technical details

References

Community reviews

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