CVE-2021-45621
📋 TL;DR
CVE-2021-45621 is a critical command injection vulnerability affecting multiple NETGEAR routers, extenders, and WiFi systems. Unauthenticated attackers can execute arbitrary commands on affected devices, potentially gaining full control. This impacts numerous NETGEAR models running outdated firmware versions.
💻 Affected Systems
- NETGEAR CBR40
- CBR750
- EAX20
- EAX80
- EX3700
- EX3800
- EX6120
- EX6130
- EX7000
- EX7500
- LAX20
- MR60
- MS60
- R6300v2
- R6400
- R6400v2
- R6700v3
- R6900P
- R7000
- R7000P
- R7100LG
- R7850
- R7900
- R7900P
- R7960P
- R8000
- R8000P
- R8300
- R8500
- RAX15
- RAX20
- RAX200
- RAX35v2
- RAX40v2
- RAX43
- RAX45
- RAX50
- RAX75
- RAX80
- RBK752
- RBK852
- RBR750
- RBR850
- RBS750
- RBS850
- RS400
- XR1000
- XR300
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, intercept all network traffic, pivot to internal networks, and use the device as part of a botnet.
Likely Case
Remote code execution leading to device takeover, credential theft, DNS hijacking, and participation in DDoS attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering, though internal network exposure remains a risk.
🎯 Exploit Status
Exploitation requires sending specially crafted HTTP requests to vulnerable endpoints. Public proof-of-concept code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions specified in the CVE description (e.g., CBR40 2.5.0.24 or later)
Vendor Advisory: https://kb.netgear.com/000064523/Security-Advisory-for-Pre-Authentication-Command-Injection-on-Some-Routers-Extenders-and-WiFi-Systems-PSV-2020-0562
Restart Required: Yes
Instructions:
1. Identify your device model and current firmware version. 2. Visit NETGEAR support website. 3. Download the latest firmware for your specific model. 4. Log into device admin interface. 5. Navigate to firmware update section. 6. Upload and install the new firmware. 7. Reboot the device.
🔧 Temporary Workarounds
Network Segmentation
allPlace affected devices behind a firewall with strict inbound filtering to block external exploitation attempts.
Disable Remote Management
allTurn off remote administration features to prevent external access to the web interface.
🧯 If You Can't Patch
- Replace affected devices with patched models or alternative vendors
- Implement strict network segmentation and monitor for suspicious traffic
🔍 How to Verify
Check if Vulnerable:
Check device firmware version via admin interface and compare against patched versions listed in the CVE.Check Version:
Log into device web interface and navigate to Advanced > Administration > Firmware Update or similar section.Verify Fix Applied:
Confirm firmware version matches or exceeds the patched version specified for your device model.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to device management interfaces
- Unexpected command execution logs
- Failed authentication attempts followed by successful exploitation
Network Indicators:
- Suspicious HTTP traffic to device IPs on management ports
- Outbound connections from devices to unknown external IPs
SIEM Query:
source="netgear_device" AND (http_uri="*cgi*" OR http_method="POST") AND http_status=200