CVE-2026-25857
📋 TL;DR
This CVE describes an OS command injection vulnerability in Tenda G300-F router firmware that allows remote attackers to execute arbitrary commands on affected devices. Attackers with access to the management interface can exploit the WAN diagnostic functionality to inject shell commands and potentially take full control of the router. Users of Tenda G300-F routers with vulnerable firmware versions are affected.
💻 Affected Systems
- Tenda G300-F router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router allowing attackers to intercept all network traffic, install persistent malware, pivot to internal networks, and potentially brick the device.
Likely Case
Attackers gain shell access to the router, enabling them to modify network settings, intercept traffic, and potentially use the device as a foothold for further attacks.
If Mitigated
If the management interface is not exposed to the internet and network segmentation is implemented, the attack surface is significantly reduced to only local network threats.
🎯 Exploit Status
Exploitation requires access to the management interface. The vulnerability is well-documented with technical details available in public references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 16.01.14.2
Vendor Advisory: https://www.tendacn.com/material/show/736333682028613
Restart Required: Yes
Instructions:
1. Log into the router's web interface. 2. Navigate to System Tools > Firmware Upgrade. 3. Download the latest firmware from Tenda's official website. 4. Upload and install the firmware update. 5. Reboot the router after installation completes.
🔧 Temporary Workarounds
Disable remote management
allPrevent external access to the router's management interface
Network segmentation
allIsolate the router management interface to a dedicated VLAN
🧯 If You Can't Patch
- Change default credentials and implement strong authentication
- Disable WAN diagnostic functionality if possible through configuration
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System Status or System Tools > Firmware UpgradeCheck Version:
Check via web interface; no direct CLI command available for end usersVerify Fix Applied:
Verify firmware version is greater than 16.01.14.2 after update📡 Detection & Monitoring
Log Indicators:
- Unusual curl commands in system logs
- Multiple failed login attempts followed by diagnostic requests
- Unexpected process execution from web interface
Network Indicators:
- Unusual outbound connections from router
- Suspicious traffic patterns from router management interface
SIEM Query:
source="router_logs" AND ("formSetWanDiag" OR "curl" AND "wan_diag")