CVE-2025-57639
📋 TL;DR
This CVE describes an OS command injection vulnerability in Tenda AC9 routers where an attacker can execute arbitrary commands on the device by manipulating the usb.samba.guest.user parameter. The vulnerability affects Tenda AC9 router users who have the Samba file sharing feature enabled. Successful exploitation could lead to complete device compromise.
💻 Affected Systems
- Tenda AC9
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full router compromise allowing attacker to intercept all network traffic, install persistent backdoors, pivot to internal network devices, and potentially brick the device.
Likely Case
Attacker gains shell access to router, can modify DNS settings, intercept credentials, disable security features, and use router as pivot point for internal network attacks.
If Mitigated
Limited impact if Samba feature is disabled or network segmentation isolates the router from critical systems.
🎯 Exploit Status
Exploitation requires access to the web management interface. The GitHub reference shows technical details but not a complete exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Tenda firmware updates for AC9 models
Vendor Advisory: Not specified in provided references
Restart Required: Yes
Instructions:
1. Log into Tenda AC9 web interface. 2. Navigate to System Tools > Firmware Upgrade. 3. Check for and install latest firmware from Tenda. 4. Reboot router after update completes.
🔧 Temporary Workarounds
Disable Samba/USB Sharing
allTurn off the vulnerable Samba file sharing feature to prevent exploitation
Restrict Web Interface Access
allLimit access to router web interface to trusted IP addresses only
🧯 If You Can't Patch
- Segment router on isolated network VLAN
- Implement network monitoring for suspicious router traffic and command execution attempts
🔍 How to Verify
Check if Vulnerable:
Check if running Tenda AC9 version 1.0 with Samba enabled. Attempt to access web interface and check firmware version.Check Version:
Log into router web interface and check System Status or About page for firmware versionVerify Fix Applied:
After firmware update, verify version is no longer 1.0. Test if command injection via usb.samba.guest.user parameter is still possible.📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in router logs
- Multiple failed login attempts to web interface
- Samba configuration changes from unexpected sources
Network Indicators:
- Unusual outbound connections from router
- DNS changes to malicious servers
- Unexpected port scans originating from router
SIEM Query:
source="router_logs" AND (command_injection OR shell_exec OR unusual_process)