CVE-2026-20777
📋 TL;DR
A heap-based buffer overflow vulnerability in libbiosig's Nicolet WFT file parser allows arbitrary code execution when processing malicious .wft files. This affects systems using libbiosig 3.9.2 or the master branch commit db9a9a63 for medical/scientific data processing.
💻 Affected Systems
- The Biosig Project libbiosig
📦 What is this software?
Libbiosig by Libbiosig Project
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control of the affected system, potentially leading to data theft, ransomware deployment, or lateral movement.
Likely Case
Remote code execution on systems processing untrusted .wft files, allowing attackers to execute arbitrary commands with the privileges of the libbiosig process.
If Mitigated
Denial of service or application crash if exploit fails, but no code execution due to security controls like ASLR or DEP.
🎯 Exploit Status
Exploitation requires the victim to process a malicious .wft file. No authentication needed if file processing is accessible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not yet released
Vendor Advisory: https://talosintelligence.com/vulnerability_reports/TALOS-2026-2362
Restart Required: Yes
Instructions:
1. Monitor The Biosig Project for security updates. 2. Apply patch when available. 3. Restart affected services after patching.
🔧 Temporary Workarounds
Disable WFT file processing
allTemporarily disable or block processing of .wft files in applications using libbiosig.
# Configuration depends on specific application using libbiosig
Input validation
allImplement strict validation of .wft files before passing to libbiosig.
# Implement file type verification and size limits in application code
🧯 If You Can't Patch
- Isolate systems using libbiosig in restricted network segments
- Implement application allowlisting to prevent unauthorized execution
🔍 How to Verify
Check if Vulnerable:
Check libbiosig version: biosig-tools --version or examine library files. If version is 3.9.2 or includes commit db9a9a63, system is vulnerable.Check Version:
biosig-tools --version 2>/dev/null || find /usr -name '*biosig*' -exec strings {} \; | grep -i versionVerify Fix Applied:
After patching, verify version is updated beyond vulnerable versions and test with known safe .wft files.📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing .wft files
- Unusual process execution from libbiosig-related processes
Network Indicators:
- Unexpected .wft file transfers to systems using libbiosig
SIEM Query:
process_name:"biosig" AND (event_type:crash OR cmdline:".wft")