CVE-2026-2907
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on Tenda HG9 routers via a stack-based buffer overflow in the GPON configuration endpoint. Attackers can exploit this by sending specially crafted requests to the /boaform/formgponConf endpoint, potentially gaining full control of affected devices. All users of Tenda HG9 routers with the vulnerable firmware are affected.
💻 Affected Systems
- Tenda HG9
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, credential theft, and use as a pivot point for attacking internal networks.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device in botnets.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering or in isolated network segments.
🎯 Exploit Status
Public exploit code is available on GitHub, making exploitation trivial for attackers with basic skills.
🛠️ 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 for HG9 model. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router after update completes.
🔧 Temporary Workarounds
Network Segmentation and Access Control
linuxBlock external access to router management interface and restrict internal access to trusted IPs only.
iptables -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
Disable GPON Configuration Endpoint
allIf possible, disable the vulnerable GPON configuration functionality through router settings.
🧯 If You Can't Patch
- Isolate affected routers in separate VLAN with strict firewall rules preventing outbound connections
- Implement network monitoring for exploitation attempts and anomalous traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 300001138 or matches affected range, device is vulnerable.Check Version:
curl -s http://router-ip/ | grep -i 'firmware\|version' or check router web interfaceVerify Fix Applied:
Verify firmware version has been updated to a version later than 300001138 and test that /boaform/formgponConf endpoint no longer accepts malformed input.📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /boaform/formgponConf with long parameter values
- Router crash/restart logs
- Unusual configuration changes
Network Indicators:
- HTTP POST requests to /boaform/formgponConf with unusually long fmgpon_loid or fmgpon_loid_password parameters
- Unexpected outbound connections from router
SIEM Query:
source="router_logs" AND (url="/boaform/formgponConf" AND (param_length>100 OR status_code=500))