CVE-2018-21163
📋 TL;DR
This CVE describes a stack-based buffer overflow vulnerability in multiple NETGEAR routers, gateways, and extenders. An authenticated attacker can exploit this to execute arbitrary code or cause denial of service. The vulnerability affects users with specific NETGEAR device models running outdated firmware versions.
💻 Affected Systems
- DGN2200Bv4
- DGN2200v4
- EX3700
- EX3800
- EX6000
- EX6100
- EX6120
- EX6130
- EX6150
- EX6200
- EX7000
- R6300v2
- R6900P
- R7000P
- R7300DST
- R7900P
- R8000
- R8000P
- WN2500RPv2
- WNDR3400v3
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network traffic interception, lateral movement to connected devices, or persistent backdoor installation.
Likely Case
Device crash/reboot causing temporary network disruption, or limited code execution within router context.
If Mitigated
No impact if patched or if attacker lacks valid credentials.
🎯 Exploit Status
Requires authentication and specific buffer overflow exploitation knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Minimum versions: DGN2200Bv4 1.0.0.102, DGN2200v4 1.0.0.102, EX3700 1.0.0.70, EX3800 1.0.0.70, EX6000 1.0.0.30, EX6100 1.0.2.22, EX6120 1.0.0.40, EX6130 1.0.0.22, EX6150 1.0.0.38, EX6200 1.0.3.86, EX7000 1.0.0.64, R6300v2 1.0.4.22, R6900P 1.3.0.18, R7000P 1.3.0.18, R7300DST 1.0.0.62, R7900P 1.3.0.10, R8000 1.0.4.12, R8000P 1.3.0.10, WN2500RPv2 1.0.1.52, WNDR3400v3 1.0.1.18
Vendor Advisory: https://kb.netgear.com/000055196/Security-Advisory-for-Post-Authentication-Stack-Overflow-on-Some-Routers-Gateways-and-Extenders-PSV-2017-0308
Restart Required: Yes
Instructions:
1. Log into NETGEAR router admin interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates or manually download from NETGEAR support site. 4. Upload and install latest firmware. 5. Reboot device.
🔧 Temporary Workarounds
Change default credentials
allChange admin password to strong unique password to reduce authentication risk.
Disable remote management
allDisable WAN-side admin access to prevent internet-based attacks.
🧯 If You Can't Patch
- Replace affected devices with supported models
- Segment network to isolate vulnerable devices
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under Advanced > Administration > Firmware Update.Check Version:
No CLI command; check via web interface at http://routerlogin.net or device IP.Verify Fix Applied:
Confirm firmware version matches or exceeds patched versions listed in advisory.📡 Detection & Monitoring
Log Indicators:
- Multiple authentication attempts
- Unexpected device reboots
- Unusual admin interface access
Network Indicators:
- Unusual outbound connections from router
- Traffic redirection anomalies
SIEM Query:
Device logs showing firmware version below patched levels OR authentication events followed by crash/reboot events.