Code execution via unchecked Tag 67 length
Published Dec 11, 2025 · Updated Dec 11, 2025
Stack-based buffer overflow in libbiosig 3.9.1 allows attackers to execute code by supplying a crafted MFER file with Tag 67. The Tag 67 branch in sopen_extended passes the file-controlled length to ifread, which writes that many bytes into the four-byte stack integer skew. Any application that parses an attacker-supplied MFER file through the library reaches the overwrite without authentication or user interaction.
Summary
What happened
Stack-based buffer overflow in libbiosig 3.9.1 allows attackers to execute code by supplying a crafted MFER file with Tag 67. The Tag 67 branch in sopen_extended passes the file-controlled length to ifread, which writes that many bytes into the four-byte stack integer skew. Any application that parses an attacker-supplied MFER file through the library reaches the overwrite without authentication or user interaction.
The record
- CVE
- CVE-2025-66046
- 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
- Dec 11, 2025CVE publishedPublication date reported by the CVE source.
- Dec 11, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=3.9.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- TALOS-2025-2296 MFER Tag 67 proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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