CVE-2025-7855
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda FH451 routers allows remote attackers to execute arbitrary code by manipulating the 'page' parameter in the /goform/qossetting endpoint. This affects Tenda FH451 routers running firmware version 1.0.0.9. Successful exploitation could lead to complete device compromise.
💻 Affected Systems
- Tenda FH451
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full router compromise, credential theft, network pivoting, and persistent backdoor installation
Likely Case
Router takeover enabling traffic interception, DNS manipulation, and network disruption
If Mitigated
Limited impact if device is behind firewall with restricted WAN access and proper network segmentation
🎯 Exploit Status
Public proof-of-concept available on GitHub, exploitation requires sending crafted HTTP request to vulnerable endpoint
🛠️ 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 web interface
Access router admin panel -> System -> Remote Management -> Disable
Network Segmentation
linuxIsolate router management interface to trusted network
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_NET -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_NET -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Replace vulnerable router with patched or different model
- Implement strict network ACLs to block all access to router management interface from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router admin interface under System Status or About pageCheck Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
Verify firmware version is no longer 1.0.0.9 after update📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to /goform/qossetting with long page parameter
- Multiple failed login attempts followed by qossetting access
Network Indicators:
- HTTP traffic to router IP on port 80/443 with abnormal POST request length
- Outbound connections from router to suspicious IPs
SIEM Query:
source="router_logs" AND (uri_path="/goform/qossetting" AND content_length>1000)