CVE-2021-45529
📋 TL;DR
This vulnerability allows an authenticated attacker to trigger a buffer overflow on affected NETGEAR routers. Successful exploitation could lead to remote code execution or denial of service. Only users with administrative credentials on vulnerable NETGEAR devices are affected.
💻 Affected Systems
- NETGEAR CBR40
- NETGEAR D7000v2
- NETGEAR D8500
- NETGEAR R6400
- NETGEAR R7000
- NETGEAR R6900P
- NETGEAR R7000P
- NETGEAR R7900
- NETGEAR R8000
- NETGEAR WNR3500Lv2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with administrative privileges, allowing complete device compromise, data theft, and lateral movement into connected networks.
Likely Case
Denial of service causing router crashes and network disruption, potentially requiring physical reset.
If Mitigated
Limited impact if strong authentication controls prevent unauthorized access to administrative interfaces.
🎯 Exploit Status
Requires authenticated access, making exploitation more difficult than unauthenticated vulnerabilities. Buffer overflow exploitation typically requires specific technical knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: CBR40 2.3.5.12, D7000v2 1.0.0.66, D8500 1.0.3.58, R6400 1.0.1.70, R7000 1.0.11.126, R6900P 1.3.2.124, R7000P 1.3.2.124, R7900 1.0.4.30, R8000 1.0.4.52, WNR3500Lv2 1.2.0.62
Vendor Advisory: https://kb.netgear.com/000064058/Security-Advisory-for-Post-Authentication-Buffer-Overflow-on-Some-Routers-PSV-2019-0077
Restart Required: Yes
Instructions:
1. Log into router admin interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates or manually download firmware from NETGEAR support site. 4. Upload and install latest firmware. 5. Router will reboot automatically.
🔧 Temporary Workarounds
Restrict administrative access
allLimit administrative interface access to trusted IP addresses only
Use strong authentication
allImplement complex passwords and consider multi-factor authentication if supported
🧯 If You Can't Patch
- Replace vulnerable devices with supported models
- Segment network to isolate vulnerable routers from critical systems
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under Advanced > Administration > Firmware UpdateCheck Version:
No CLI command - check via web interface at router IP addressVerify Fix Applied:
Confirm firmware version matches or exceeds patched versions listed in advisory📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by buffer overflow patterns
- Router crash/reboot logs
- Unusual administrative access from unexpected sources
Network Indicators:
- Unusual traffic patterns from router administrative interface
- Router becoming unresponsive to legitimate requests
SIEM Query:
source="router_logs" AND (event_type="authentication_failure" OR event_type="system_crash") AND device_model IN ("CBR40", "D7000v2", "D8500", "R6400", "R7000", "R6900P", "R7000P", "R7900", "R8000", "WNR3500Lv2")