CVE-2025-1851
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Tenda AC7 routers allows remote attackers to execute arbitrary code by manipulating the firewallEn parameter. This affects all Tenda AC7 routers running firmware up to version 15.03.06.44. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Tenda AC7
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, enabling attackers to install malware, pivot to internal networks, or create persistent backdoors.
Likely Case
Remote code execution resulting in device takeover, network traffic interception, or participation in botnets.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering, though internal network exposure remains a risk.
🎯 Exploit Status
Public exploit code is available in GitHub repositories. The vulnerability requires sending a specially crafted HTTP POST request to /goform/SetFirewallCfg with manipulated firewallEn parameter.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.tenda.com.cn/
Restart Required: Yes
Instructions:
1. Check Tenda's official website for firmware updates. 2. If update is available, download the latest firmware. 3. Log into router admin interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and install the new firmware. 6. Reboot the router.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to the router's web interface by disabling remote management features.
Network Segmentation
allIsolate Tenda AC7 routers in a separate VLAN with strict firewall rules limiting access to management interfaces.
🧯 If You Can't Patch
- Replace vulnerable Tenda AC7 routers with different models or brands that are not affected.
- Implement strict network access controls to limit traffic to router management interfaces from trusted IP addresses only.
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: Login > System Tools > Firmware Upgrade. If version is 15.03.06.44 or lower, device is vulnerable.Check Version:
curl -s http://router-ip/goform/GetModuleInfo | grep -i version (if web interface accessible)Verify Fix Applied:
After updating, verify firmware version shows higher than 15.03.06.44 in the same interface.📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /goform/SetFirewallCfg with unusual firewallEn parameter values
- Router crash/reboot logs
- Unusual outbound connections from router
Network Indicators:
- HTTP POST requests to router IP on port 80/443 targeting /goform/SetFirewallCfg with long firewallEn parameters
- Sudden changes in router configuration
SIEM Query:
source="router_logs" AND (uri="/goform/SetFirewallCfg" OR message="firewallEn") AND bytes>1000