CVE-2018-21153
📋 TL;DR
This CVE describes a critical buffer overflow vulnerability in multiple NETGEAR routers, gateways, and extenders that allows unauthenticated remote attackers to execute arbitrary code. The vulnerability affects devices with firmware versions below specified thresholds. Attackers can exploit this without any authentication, making it particularly dangerous.
💻 Affected Systems
- NETGEAR D7800
- DM200
- EX2700
- EX6100v2
- EX6150v2
- EX6200v2
- EX6400
- EX7300
- EX8000
- R6100
- R7500
- R7500v2
- R7800
- R8900
- R9000
- WN2000RPTv3
- WN3000RPv2
- WN3000RPv3
- WN3100RPv2
- WNDR4300
- WNDR4300v2
- WNDR4500v3
- WNR2000v5
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, credential theft, and lateral movement to connected devices.
Likely Case
Remote code execution leading to device takeover, creation of botnet nodes, or deployment of ransomware/malware on the network.
If Mitigated
Limited impact if devices are behind firewalls with strict ingress filtering and network segmentation.
🎯 Exploit Status
Public exploit code exists for this vulnerability. The CVSS score of 9.8 indicates trivial exploitation with high impact.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Varies by model - see CVE description for specific minimum safe versions for each device.
Vendor Advisory: https://kb.netgear.com/000059480/Security-Advisory-for-Pre-Authentication-Buffer-Overflow-on-Some-Gateways-Routers-and-Extenders-PSV-2017-3136
Restart Required: Yes
Instructions:
1. Identify your NETGEAR device model. 2. Log into the router admin interface. 3. Navigate to Advanced > Administration > Firmware Update. 4. Check for updates and install the latest firmware. 5. Alternatively, download firmware from NETGEAR support site and manually upload via admin interface.
🔧 Temporary Workarounds
Network Segmentation
allPlace affected devices in isolated network segments with strict firewall rules limiting inbound traffic.
Disable Remote Management
allDisable remote administration/WAN access to router management interface.
🧯 If You Can't Patch
- Replace affected devices with patched models or alternative vendors
- Implement strict network segmentation and firewall rules to limit device exposure
🔍 How to Verify
Check if Vulnerable:
Check router admin interface for firmware version and compare against minimum safe versions listed in CVE description.Check Version:
Access router web interface at http://routerlogin.net or device IP, navigate to Advanced > Administration > Firmware Update to view current version.Verify Fix Applied:
Verify firmware version is at or above the minimum safe version for your specific device model.📡 Detection & Monitoring
Log Indicators:
- Unusual buffer overflow errors in router logs
- Multiple failed exploitation attempts
- Unexpected device reboots or crashes
Network Indicators:
- Unusual outbound traffic from router
- Unexpected connections to known malicious IPs
- Anomalous HTTP requests to router management interface
SIEM Query:
source="router_logs" AND ("buffer overflow" OR "segmentation fault" OR "kernel panic")