CVE-2021-45527
📋 TL;DR
This CVE describes a post-authentication buffer overflow vulnerability in multiple NETGEAR routers, extenders, and WiFi systems. An authenticated attacker could exploit this to execute arbitrary code or cause denial of service. The vulnerability affects numerous NETGEAR device models with specific firmware versions.
💻 Affected Systems
- NETGEAR D6220
- D6400
- D7000v2
- D8500
- DC112A
- EX7000
- EX7500
- R6250
- R6300v2
- R6400
- R6400v2
- R6700v3
- R7000
- R7100LG
- R7850
- R7900
- R7960P
- R8000
- RAX200
- RBS40V
- RS400
- XR300
- R7000P
- R8000P
- R8500
- RAX80
- R6900P
- R7900P
- R8300
- RAX75
- RBR750
- RBR850
- RBS750
- RBS850
- RBK752
- RBK852
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing remote code execution, network takeover, credential theft, and lateral movement to connected devices.
Likely Case
Device crash/reboot causing denial of service, potential for limited code execution to modify device settings or intercept traffic.
If Mitigated
Minimal impact if proper network segmentation and access controls prevent authenticated attackers from reaching vulnerable interfaces.
🎯 Exploit Status
Exploitation requires valid credentials to the device, making it post-authentication. Buffer overflow (CWE-120) typically requires crafting specific input to trigger.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions specified in CVE description (e.g., D6220 1.0.0.68 or later)
Vendor Advisory: https://kb.netgear.com/000064493/Security-Advisory-for-Post-Authentication-Buffer-Overflow-on-Some-Routers-Extenders-and-WiFi-Systems-PSV-2020-0437
Restart Required: Yes
Instructions:
1. Log into NETGEAR router web interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates and apply if available. 4. Alternatively, download firmware from NETGEAR support site and manually upload. 5. Reboot device after update.
🔧 Temporary Workarounds
Restrict management access
allLimit access to router management interface to trusted IP addresses only
Change default credentials
allEnsure strong, unique passwords are set for all administrative accounts
🧯 If You Can't Patch
- Segment network to isolate vulnerable devices from critical assets
- Implement strict access controls and monitor for suspicious authentication attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under Advanced > Administration > Firmware Update or via routerinfo.html pageCheck Version:
curl http://routerlogin.net/routerinfo.html | grep FirmwareVerify Fix Applied:
Confirm firmware version matches or exceeds patched versions listed in CVE description📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by successful login and unusual POST requests
- Device crash/reboot logs
Network Indicators:
- Unusual outbound connections from router
- Traffic interception patterns
SIEM Query:
source="router.log" (event="authentication success" AND event="POST /" AND status=200)