CVE-2025-31355
📋 TL;DR
A firmware signature validation bypass vulnerability in Tenda AC6 routers allows attackers to upload malicious firmware updates, leading to arbitrary code execution. This affects Tenda AC6 V5.0 routers running firmware version V02.03.01.110. Attackers with network access to the router's management interface can exploit this.
💻 Affected Systems
- Tenda AC6 V5.0
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router compromise allowing persistent backdoor installation, traffic interception, credential theft, and pivot to internal networks.
Likely Case
Router takeover enabling DNS hijacking, credential harvesting, and network surveillance.
If Mitigated
Limited to authenticated attackers with network access to management interface.
🎯 Exploit Status
Exploitation requires network access to router management interface and ability to upload firmware file.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda website for firmware updates
2. Download latest firmware for AC6 V5.0
3. Log into router web interface
4. Navigate to System Tools > Firmware Upgrade
5. Upload and install new firmware
6. Reboot router
🔧 Temporary Workarounds
Disable remote management
allPrevent external access to router management interface
Network segmentation
allIsolate router management interface to trusted network
🧯 If You Can't Patch
- Replace vulnerable router with different model/brand
- Implement strict network access controls to router management interface
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in web interface under System Status or via SSH if enabled.Check Version:
Login to router web interface and check System Status pageVerify Fix Applied:
Verify firmware version is no longer V02.03.01.110 after update.📡 Detection & Monitoring
Log Indicators:
- Unexpected firmware update attempts
- Unauthorized firmware file uploads
- System reboot after firmware update
Network Indicators:
- HTTP POST requests to firmware update endpoints
- Unusual traffic patterns from router
SIEM Query:
source="router_logs" AND (event="firmware_update" OR event="system_reboot")