CVE-2026-2905
📋 TL;DR
A stack-based buffer overflow vulnerability in Tenda HG9 routers allows remote attackers to execute arbitrary code by manipulating the ssid parameter in the Wireless Configuration Endpoint. This affects Tenda HG9 routers with firmware version 300001138. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda HG9
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement to internal networks, and persistent backdoor installation.
Likely Case
Router takeover enabling traffic interception, DNS manipulation, credential theft, and denial of service.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Public exploit code exists in GitHub repositories. Attack requires sending specially crafted HTTP POST requests to /boaform/formWlanSetup.
🛠️ 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
Disable Remote Management
allPrevent external access to router management interface
Access router admin > Advanced > Remote Management > Disable
Network Segmentation
linuxIsolate router management interface to trusted network
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_NETWORK -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
🧯 If You Can't Patch
- Place router behind firewall with strict inbound filtering (block WAN access to port 80/443)
- Implement network segmentation to limit router exposure to minimal necessary networks
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under System Status or About page. If version is 300001138, device is vulnerable.Check Version:
curl -s http://router-ip/ | grep -i 'firmware\|version' or check router web interfaceVerify Fix Applied:
After firmware update, verify version has changed from 300001138 and test if /boaform/formWlanSetup endpoint still accepts malformed ssid parameters.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /boaform/formWlanSetup with unusually long ssid parameters
- Router crash/reboot logs
- Unusual process execution in router logs
Network Indicators:
- HTTP traffic to router IP on port 80 with POST to /boaform/formWlanSetup
- Unusual outbound connections from router after exploitation
SIEM Query:
source="router_logs" AND (url="/boaform/formWlanSetup" AND method="POST" AND content_length>100) OR (event="crash" AND device="Tenda_HG9")