CVE-2021-45555
📋 TL;DR
This vulnerability allows authenticated attackers to execute arbitrary commands on affected NETGEAR routers. It affects R7900P, R7960P, and R8000P models running firmware versions before 1.4.2.84. Attackers must have valid credentials to exploit this command injection flaw.
💻 Affected Systems
- NETGEAR R7900P
- NETGEAR R7960P
- NETGEAR R8000P
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router compromise allowing attackers to intercept traffic, install persistent backdoors, pivot to internal networks, or brick the device.
Likely Case
Attackers with stolen or default credentials gain full control of the router to monitor traffic, change DNS settings, or deploy malware.
If Mitigated
Limited to authenticated users only, so strong unique passwords and network segmentation reduce impact.
🎯 Exploit Status
Exploitation requires valid credentials but is straightforward once authenticated. Public exploit code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.2.84 or later
Vendor Advisory: https://kb.netgear.com/000064497/Security-Advisory-for-Post-Authentication-Command-Injection-on-Some-Routers-PSV-2020-0480
Restart Required: Yes
Instructions:
1. Log into router web interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates and install firmware 1.4.2.84 or later. 4. Reboot router after update completes.
🔧 Temporary Workarounds
Change Default Credentials
allUse strong unique passwords for router admin accounts to prevent unauthorized authentication.
Disable Remote Management
allPrevent external access to router administration interface.
🧯 If You Can't Patch
- Isolate router on separate VLAN with strict access controls
- Implement network monitoring for suspicious router command execution
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in web interface under Advanced > Administration > Firmware Update.Check Version:
Check via web interface or SSH if enabled: cat /etc/versionVerify Fix Applied:
Confirm firmware version is 1.4.2.84 or later in router administration interface.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in router logs
- Multiple failed login attempts followed by successful login and command execution
Network Indicators:
- Unexpected outbound connections from router
- DNS changes or unusual traffic patterns
SIEM Query:
source="router_logs" AND (command="*;*" OR command="*|*" OR command="*`*" OR command="*$(*")