CVE-2019-20734
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to execute arbitrary code on affected NETGEAR routers and extenders via a buffer overflow. It affects multiple NETGEAR device models with outdated firmware versions. Attackers can potentially gain full control of vulnerable devices without any authentication.
💻 Affected Systems
- NETGEAR D6220
- D8500
- EX3700
- EX3800
- EX6000
- EX6100
- EX6120
- EX6130
- EX6150v1
- EX6200
- EX7000
- R6300v2
- R6400
- R6400v2
- R6700
- R6700v3
- R6900
- R7000
- R6900P
- R7000P
- R7100LG
- R7300DST
- R7900
- R8300
- R8500
- WN2500RPv2
- WNR3500Lv2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to install persistent malware, intercept all network traffic, pivot to internal networks, or join botnets.
Likely Case
Device takeover leading to DNS hijacking, credential theft, man-in-the-middle attacks, or denial of service.
If Mitigated
No impact if devices are patched or properly segmented behind firewalls.
🎯 Exploit Status
Buffer overflow vulnerabilities in network devices are commonly weaponized. The unauthenticated nature and CVSS 8.8 score make this attractive to attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Varies by model - see minimum secure versions in description
Vendor Advisory: https://kb.netgear.com/000061192/Security-Advisory-for-Pre-Authentication-Buffer-Overflow-on-Some-Routers-Gateways-and-Extenders-PSV-2017-0791
Restart Required: Yes
Instructions:
1. Identify your NETGEAR model number. 2. Visit NETGEAR support site. 3. Download latest firmware for your model. 4. Log into router admin interface. 5. Navigate to Advanced > Administration > Firmware Update. 6. Upload and install the firmware file. 7. Wait for automatic reboot.
🔧 Temporary Workarounds
Network Segmentation
allPlace vulnerable devices behind a firewall to block external exploitation attempts
Disable Remote Management
allTurn off remote administration features to reduce attack surface
🧯 If You Can't Patch
- Replace vulnerable devices with supported models that receive security updates
- Implement strict network segmentation and firewall rules to isolate vulnerable devices
🔍 How to Verify
Check if Vulnerable:
Check router admin interface for model and firmware version, compare against affected versions listCheck Version:
Access router web interface at http://routerlogin.net or http://192.168.1.1, navigate to Advanced > Administration > Router StatusVerify Fix Applied:
Verify firmware version matches or exceeds minimum secure version for your model📡 Detection & Monitoring
Log Indicators:
- Unusual firmware modification logs
- Multiple failed exploit attempts in web server logs
- Unexpected device reboots
Network Indicators:
- Unusual outbound connections from router
- DNS hijacking patterns
- Traffic redirection to suspicious IPs
SIEM Query:
source="router_logs" AND (event="firmware_change" OR event="buffer_overflow_attempt" OR event="unauth_access")