CVE-2025-57071
📋 TL;DR
A stack overflow vulnerability in Tenda G3 routers allows attackers to cause Denial of Service (DoS) by sending specially crafted requests to the VPN users configuration function. This affects Tenda G3 routers running vulnerable firmware versions, potentially disrupting network connectivity for all users.
💻 Affected Systems
- Tenda G3
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router crash requiring physical reboot, persistent network downtime, and potential for remote code execution if the overflow can be leveraged for arbitrary code execution.
Likely Case
Router becomes unresponsive, requiring reboot to restore functionality, causing temporary network disruption for all connected devices.
If Mitigated
No impact if the vulnerable interface is not exposed to untrusted networks or if traffic is filtered.
🎯 Exploit Status
Exploitation requires access to the router's web interface, which typically requires authentication. The vulnerability is in the formAddVpnUsers function handling the vpnUsers parameter.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda's official website for firmware updates. 2. Download the latest firmware for G3. 3. Access router web interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and install the new firmware. 6. Reboot the router.
🔧 Temporary Workarounds
Disable VPN functionality
allTurn off VPN features if not required to remove the attack surface.
Restrict web interface access
allLimit access to the router's management interface to trusted IP addresses only.
🧯 If You Can't Patch
- Isolate the router on a separate network segment with strict firewall rules
- Implement network monitoring for unusual traffic patterns to the router's management interface
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: System Status > Firmware Version. If version is v3.0br_V15.11.0.17 or earlier, it is vulnerable.Check Version:
Not applicable - check via web interfaceVerify Fix Applied:
After updating, verify the firmware version has changed from v3.0br_V15.11.0.17 to a newer version.📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by large POST requests to /goform/AddVpnUsers
- Router reboot logs without user action
Network Indicators:
- Unusual HTTP POST requests to router IP on port 80/443 with oversized vpnUsers parameter
- Sudden loss of connectivity to router management interface
SIEM Query:
source="router_logs" AND (uri_path="/goform/AddVpnUsers" AND content_length>1000)