CVE-2021-46408
📋 TL;DR
A stack buffer overflow vulnerability exists in Tenda AX12 routers running firmware v22.03.01.21. Attackers can exploit this via the strcpy parameter to cause a Denial of Service (DoS), potentially crashing the device. This affects all users of the vulnerable firmware version.
💻 Affected Systems
- Tenda AX12
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device crash requiring physical reboot, potential remote code execution if the overflow can be controlled precisely (though not confirmed in this CVE).
Likely Case
Router becomes unresponsive, requiring reboot and causing temporary network disruption for connected devices.
If Mitigated
Minimal impact if device is behind firewall with no external access to vulnerable interface.
🎯 Exploit Status
Public proof-of-concept exists in GitHub repositories. The strcpy vulnerability suggests straightforward exploitation for DoS.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda website for firmware updates. 2. Download latest firmware. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Network Segmentation
allIsolate router from untrusted networks to limit attack surface
Access Control
allRestrict administrative access to trusted IP addresses only
🧯 If You Can't Patch
- Replace vulnerable device with patched or different model
- Implement network monitoring for DoS attempts against the router
🔍 How to Verify
Check if Vulnerable:
Access router admin interface and check firmware version in system settingsCheck Version:
Check via web interface at router IP (typically 192.168.0.1 or 192.168.1.1)Verify Fix Applied:
Verify firmware version is no longer v22.03.01.21 after update📡 Detection & Monitoring
Log Indicators:
- Router crash/reboot events
- Unusual traffic to router management interface
Network Indicators:
- Multiple connection attempts to router on unusual ports
- Traffic patterns matching known exploit payloads
SIEM Query:
source="router_logs" AND (event="crash" OR event="reboot") OR dest_ip="router_ip" AND protocol="http" AND size>threshold