CVE-2021-45508
📋 TL;DR
This CVE describes an authentication bypass vulnerability in specific NETGEAR WiFi systems. Attackers can potentially gain unauthorized access to device administration interfaces without valid credentials. Affected users include those running vulnerable firmware versions on CBR40, CBR750, RBK752, RBR750, RBS750, RBK852, and RBR850 devices.
💻 Affected Systems
- NETGEAR CBR40
- NETGEAR CBR750
- NETGEAR RBK752
- NETGEAR RBR750
- NETGEAR RBS750
- NETGEAR RBK852
- NETGEAR RBR850
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full administrative control of affected devices, allowing attackers to reconfigure networks, intercept traffic, install malware, or use devices as attack platforms.
Likely Case
Unauthorized access to device management interfaces leading to network configuration changes, credential theft, or denial of service.
If Mitigated
Limited impact if devices are behind firewalls, have strong network segmentation, and use additional authentication layers.
🎯 Exploit Status
Authentication bypass vulnerabilities typically have low exploitation complexity. No public exploit code was found in initial research.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: CBR40: 2.5.0.24+, CBR750: 4.6.3.6+, RBK752/RBR750/RBS750: 3.2.17.12+, RBK852/RBR850: 3.2.17.12+
Vendor Advisory: https://kb.netgear.com/000064133/Security-Advisory-for-Authentication-Bypass-on-Some-WiFi-Systems-PSV-2020-0490
Restart Required: Yes
Instructions:
1. Log into device admin interface. 2. Navigate to Advanced > Administration > Firmware Update. 3. Check for updates. 4. If update available, download and install. 5. Device will reboot automatically.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected devices in separate VLANs with strict firewall rules limiting access to management interfaces.
Access Control Lists
allImplement ACLs to restrict access to device management interfaces to trusted IP addresses only.
🧯 If You Can't Patch
- Disable remote management and WAN-side administration interfaces
- Implement network monitoring for unauthorized access attempts to device management ports
🔍 How to Verify
Check if Vulnerable:
Access device web interface, navigate to Advanced > Administration > Firmware Update, check current firmware version against affected versions list.Check Version:
Check via web interface: Advanced > Administration > Firmware Update shows current versionVerify Fix Applied:
Verify firmware version matches or exceeds patched versions listed in vendor advisory.📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts to admin interfaces
- Multiple failed login attempts followed by successful access without valid credentials
- Configuration changes from unexpected IP addresses
Network Indicators:
- Unusual traffic to device management ports (typically 80/443)
- Administrative access from unexpected network segments
SIEM Query:
source_ip=* AND (dest_port=80 OR dest_port=443) AND dest_ip=[device_ip] AND (http_method=POST OR http_method=GET) AND uri_path CONTAINS "/" AND NOT user_agent CONTAINS "browser_string"