CVE-2021-45638
📋 TL;DR
This CVE describes a critical stack-based buffer overflow vulnerability in multiple NETGEAR router models that allows unauthenticated remote attackers to execute arbitrary code. The vulnerability affects specific firmware versions of various NETGEAR D, R, and other series routers. Attackers can exploit this without any authentication to potentially take full control of affected devices.
💻 Affected Systems
- NETGEAR D6220
- D6400
- D7000v2
- D8500
- DC112A
- R6300v2
- R6400
- R7000
- R7100LG
- RBS40V
- RBW30
- RS400
- R7000P
- R6900P
📦 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, and create botnet nodes.
Likely Case
Remote code execution leading to device takeover, network traffic interception, and potential lateral movement to connected devices.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering, though internal network exposure remains a risk.
🎯 Exploit Status
The vulnerability is pre-authentication and has been publicly disclosed with technical details, making exploitation relatively straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: See affected_systems.versions for minimum fixed versions per model
Vendor Advisory: https://kb.netgear.com/000064496/Security-Advisory-for-Pre-Authentication-Stack-Overflow-on-Some-Routers-PSV-2020-0464
Restart Required: Yes
Instructions:
1. Identify your router model and current firmware version. 2. Visit NETGEAR support website. 3. Download the latest firmware for your specific model. 4. Log into router admin interface. 5. Navigate to Advanced > Administration > Firmware Update. 6. Upload and install the firmware file. 7. Wait for router to reboot automatically.
🔧 Temporary Workarounds
Disable Remote Management
allDisable remote administration/management features to prevent external exploitation attempts
Network Segmentation
allPlace routers in isolated network segments with strict firewall rules limiting inbound access
🧯 If You Can't Patch
- Replace affected devices with patched models or different vendors
- Implement strict network segmentation and firewall rules to limit router exposure
🔍 How to Verify
Check if Vulnerable:
Check router admin interface for model and firmware version, compare against affected versions listCheck Version:
Login to router web interface and check under Advanced > Administration > Router Status or similar sectionVerify Fix Applied:
Verify firmware version in admin interface matches or exceeds the patched version for your model📡 Detection & Monitoring
Log Indicators:
- Unusual authentication attempts
- Firmware modification logs
- Unexpected reboots or crashes
Network Indicators:
- Unusual outbound connections from router
- Traffic redirection anomalies
- DNS hijacking patterns
SIEM Query:
source="router_logs" AND (event_type="buffer_overflow" OR event_type="firmware_change" OR event_type="unauthorized_access")