CVE-2026-2909
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on Tenda HG9 routers via a stack-based buffer overflow in the Diagnostic Ping Endpoint. Attackers can exploit this by sending specially crafted requests to the /boaform/formPing 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 allowing attackers to install persistent malware, intercept network traffic, pivot to internal networks, or use the device as part of a botnet.
Likely Case
Remote code execution leading to device takeover, network disruption, and potential credential theft from connected devices.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering, though internal exploitation remains possible.
🎯 Exploit Status
Public exploit details are available on GitHub, making this easily weaponizable. The buffer overflow manipulation of pingAddr parameter is straightforward.
🛠️ 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 administration interface
Block Access to Diagnostic Ping Endpoint
linuxUse firewall rules to block access to /boaform/formPing
iptables -A INPUT -p tcp --dport 80 -m string --string "/boaform/formPing" --algo bm -j DROP
🧯 If You Can't Patch
- Isolate affected routers in separate network segments with strict firewall rules
- Implement network monitoring for exploitation attempts and block malicious IPs
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 300001138, device is vulnerable.Check Version:
Login to router admin interface and check System Status or Firmware Information pageVerify Fix Applied:
Verify firmware version has changed from 300001138 after update. Test if /boaform/formPing endpoint still accepts pingAddr parameter with long strings.📡 Detection & Monitoring
Log Indicators:
- Unusually long pingAddr parameters in web logs
- Multiple failed exploitation attempts to /boaform/formPing
Network Indicators:
- HTTP POST requests to /boaform/formPing with oversized pingAddr values
- Traffic patterns suggesting buffer overflow exploitation
SIEM Query:
source="router_logs" AND uri="/boaform/formPing" AND (payload_size>1000 OR contains(payload, "pingAddr="))