CVE-2025-66043Public exploitNetwork attack vector

Code execution via unchecked MFER Tag 3 length

Published Dec 11, 2025 · Updated Dec 11, 2025

Stack-based buffer overflow in The BioSig Project libbiosig 3.9.1 allows attackers to execute arbitrary code via a crafted MFER file. In the MFER Tag 3 branch of sopen_extended, ifread copies an attacker-controlled length into the 17-byte stack buffer v after an oversized-length check only prints a warning. Processing a malicious MFER file is sufficient to overwrite adjacent stack data, causing a crash or enabling code execution in the calling process.

CVSS severity9.8
Critical
EPSS probability0.71%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stack-based buffer overflow in The BioSig Project libbiosig 3.9.1 allows attackers to execute arbitrary code via a crafted MFER file. In the MFER Tag 3 branch of sopen_extended, ifread copies an attacker-controlled length into the 17-byte stack buffer v after an oversized-length check only prints a warning. Processing a malicious MFER file is sufficient to overwrite adjacent stack data, causing a crash or enabling code execution in the calling process.

The record

CVE
CVE-2025-66043
Published
Dec 11, 2025
Updated
Dec 11, 2025
Vendor
The BioSig Project
Product
libbiosig
Classifications
CWE-121, CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 11, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The BioSig Project · libbiosigversion=3.9.1

Published CVSS scores

9.8Cisco TalosCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo