CVE-2025-12209
📋 TL;DR
A stack-based buffer overflow vulnerability in Tenda O3 routers allows remote attackers to execute arbitrary code by manipulating the dhcpEn parameter in the SetValue/GetValue function. This affects Tenda O3 router firmware version 1.0.0.10(2478). Attackers can exploit this from the network without authentication.
💻 Affected Systems
- Tenda O3 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network infiltration, and potential lateral movement to other systems.
Likely Case
Router takeover allowing traffic interception, DNS manipulation, credential theft, and deployment of persistent malware.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access, though internal network exposure remains.
🎯 Exploit Status
Public exploit documentation exists on GitHub, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.tenda.com.cn/
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 Tenda O3 routers in separate VLAN with strict firewall rules.
Access Control
linuxBlock external access to router admin interface using firewall rules.
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace affected routers with different models that receive security updates
- Implement strict network monitoring and intrusion detection for router traffic
🔍 How to Verify
Check if Vulnerable:
Access router web interface, navigate to System Status or About page, check firmware version matches 1.0.0.10(2478).Check Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
After firmware update, verify version no longer shows 1.0.0.10(2478) and check for newer version number.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/setDhcpConfig
- Multiple failed buffer overflow attempts in system logs
- Unexpected router reboots or configuration changes
Network Indicators:
- Unusual traffic patterns to router management interface
- Suspicious payloads containing dhcpEn parameter manipulation
- Traffic from unexpected sources to router port 80/443
SIEM Query:
source="router_logs" AND (uri="/goform/setDhcpConfig" OR message="buffer overflow" OR message="dhcpEn")