CVE-2021-38527
📋 TL;DR
This vulnerability allows unauthenticated attackers to execute arbitrary commands on affected NETGEAR devices via command injection. It affects multiple NETGEAR routers, extenders, and WiFi systems running vulnerable firmware versions. Attackers can exploit this without any authentication.
💻 Affected Systems
- NETGEAR CBR40
- EX6100v2
- EX6150v2
- EX6250
- EX6400
- EX6400v2
- EX6410
- EX6420
- EX7300
- EX7300v2
- EX7320
- EX7700
- EX8000
- R7800
- RBK12
- RBR10
- RBS10
- RBK20
- RBR20
- RBS20
- RBK40
- RBR40
- RBS40
- RBK50
- RBR50
- RBS50
- RBK752
- RBR750
- RBS750
- RBK852
- RBR850
- RBS850
- RBS40V
- RBS50Y
- RBW30
- XR500
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent malware, pivot to internal networks, intercept traffic, or brick devices.
Likely Case
Attackers gain remote code execution to install cryptocurrency miners, create botnet nodes, or steal credentials from connected devices.
If Mitigated
With proper network segmentation and firewalls, impact is limited to the affected device only.
🎯 Exploit Status
Command injection vulnerabilities are typically easy to exploit. Public exploit code exists for similar NETGEAR vulnerabilities.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions specified in CVE description (e.g., CBR40 2.5.0.14+, EX6100v2 1.0.1.98+, etc.)
Vendor Advisory: https://kb.netgear.com/000063778/Security-Advisory-for-Pre-Authentication-Command-Injection-on-Some-Extenders-Routers-and-WiFi-Systems-PSV-2020-0025
Restart Required: Yes
Instructions:
1. Log into device web interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates. 4. If update available, download and install. 5. Device will reboot automatically.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected devices from internet and critical internal networks
Firewall Rules
allBlock all inbound WAN access to device management interfaces
🧯 If You Can't Patch
- Replace affected devices with patched models or different vendors
- Place devices behind VPN-only access with multi-factor authentication
🔍 How to Verify
Check if Vulnerable:
Check firmware version in device web interface under Advanced > Administration > Firmware UpdateCheck Version:
No CLI command available. Use web interface at http://[device-ip]Verify Fix Applied:
Confirm firmware version matches or exceeds patched versions listed in CVE description📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed login attempts followed by successful access
- Unexpected system reboots or configuration changes
Network Indicators:
- Unusual outbound connections from device
- Traffic to known malicious IPs
- Port scans originating from device
SIEM Query:
source="netgear-device" AND (event_type="command_execution" OR event_type="system_reboot")