CVE-2026-3802
📋 TL;DR
A remote stack-based buffer overflow vulnerability in Tenda i3 routers allows attackers to execute arbitrary code by manipulating the cmdinput parameter in the formexeCommand function. This affects Tenda i3 router users running vulnerable firmware versions. Successful exploitation could lead to complete device compromise.
💻 Affected Systems
- Tenda i3 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full router compromise, network traffic interception, credential theft, and lateral movement to connected devices.
Likely Case
Router takeover enabling DNS hijacking, network monitoring, or botnet recruitment.
If Mitigated
Denial of service or temporary disruption if exploit fails or is blocked.
🎯 Exploit Status
Public exploit code available 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
Disable remote administration
allPrevent external access to router administration interface
Network segmentation
allIsolate router management interface to trusted network segment
🧯 If You Can't Patch
- Replace vulnerable router with different model
- Implement strict firewall rules blocking access to router management interface from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 1.0.0.6(2204), device is vulnerable.Check Version:
Check router web interface or use nmap/router scanning tools to identify firmware version.Verify Fix Applied:
Verify firmware version has changed from 1.0.0.6(2204) to a newer version.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/exeCommand
- Multiple failed exploit attempts
- Router reboot events
Network Indicators:
- Unusual traffic patterns to router management interface
- Suspicious payloads in HTTP requests
SIEM Query:
http.url:"/goform/exeCommand" AND http.method:POST AND http.user_agent contains suspicious patterns