CVE-2026-3677
📋 TL;DR
A stack-based buffer overflow vulnerability in Tenda FH451 routers allows remote attackers to execute arbitrary code by manipulating the funcname/funcpara1 arguments in the fromSetCfm function. This affects Tenda FH451 routers running firmware version 1.0.0.9. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda FH451
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement into internal networks, and persistent backdoor installation.
Likely Case
Device takeover enabling traffic interception, credential theft, and participation in botnets.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Public exploit code exists and remote exploitation requires no authentication.
🛠️ 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 WAN Management
allPrevent remote access to router administration interface from internet
Network Segmentation
allIsolate router management interface to separate VLAN
🧯 If You Can't Patch
- Replace affected routers with supported models
- Implement strict firewall rules blocking all inbound traffic to router management interfaces
🔍 How to Verify
Check if Vulnerable:
Access router web interface, navigate to System Status or About page, check firmware version equals 1.0.0.9Check Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
Verify firmware version is higher than 1.0.0.9 after update📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/setcfm with long funcname/funcpara1 parameters
- Multiple failed exploit attempts
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns suggesting device compromise
SIEM Query:
source="router_logs" AND url="/goform/setcfm" AND (param_length>100 OR status_code=500)