CVE-2025-4139
📋 TL;DR
A critical buffer overflow vulnerability in Netgear EX6120's fwAcosCgiInbound function allows remote attackers to execute arbitrary code by manipulating the 'host' argument. This affects Netgear EX6120 devices running firmware version 1.0.0.68. The vulnerability is remotely exploitable without authentication.
💻 Affected Systems
- Netgear EX6120
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network pivoting, and persistent backdoor installation.
Likely Case
Device crash/reboot (DoS) or limited code execution to modify device settings.
If Mitigated
Denial of service if exploit fails but triggers overflow.
🎯 Exploit Status
Public PoC available on GitHub; remote exploitation without authentication makes weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.netgear.com/
Restart Required: Yes
Instructions:
1. Check Netgear support for firmware updates. 2. If update available, download from official site. 3. Upload via web interface. 4. Reboot device.
🔧 Temporary Workarounds
Network Segmentation
allIsolate EX6120 devices from untrusted networks and internet exposure.
Access Control Lists
allRestrict management interface access to trusted IPs only.
🧯 If You Can't Patch
- Replace with patched or different model if vendor doesn't provide fix.
- Monitor for suspicious traffic to/from EX6120 devices.
🔍 How to Verify
Check if Vulnerable:
Check firmware version in web interface: Settings > Administration > Firmware Update.Check Version:
Check web interface or use nmap -sV -p 80,443 <device_ip>Verify Fix Applied:
Verify firmware version is NOT 1.0.0.68 after update.📡 Detection & Monitoring
Log Indicators:
- Repeated device reboots
- Unusual CGI requests to fwAcosCgiInbound
Network Indicators:
- HTTP requests with long host parameters to EX6120
SIEM Query:
source="EX6120" AND (event="reboot" OR uri="*fwAcosCgiInbound*")