CVE-2025-9813
📋 TL;DR
A buffer overflow vulnerability in Tenda CH22 router firmware allows remote attackers to execute arbitrary code or crash the device by sending specially crafted requests to the /goform/SetSambaConf endpoint. This affects Tenda CH22 routers running firmware version 1.0.0.1. The vulnerability is remotely exploitable without authentication.
💻 Affected Systems
- Tenda CH22
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, lateral movement to internal networks, and persistent backdoor installation.
Likely Case
Device crash causing denial of service, potential information disclosure, or limited code execution depending on exploit sophistication.
If Mitigated
Denial of service only if exploit attempts are blocked or fail to achieve code execution.
🎯 Exploit Status
Exploit code is publicly available on GitHub, making this easily weaponizable. The vulnerability requires no authentication and has low exploitation complexity.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.tenda.com.cn/
Restart Required: Yes
Instructions:
1. Check Tenda website for firmware updates. 2. Download latest firmware for CH22. 3. Log into router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router after update.
🔧 Temporary Workarounds
Disable Remote Management
allDisable web management interface from WAN/Internet to prevent remote exploitation
Block Vulnerable Endpoint
linuxUse firewall rules to block access to /goform/SetSambaConf endpoint
iptables -A INPUT -p tcp --dport 80 -m string --string "/goform/SetSambaConf" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/goform/SetSambaConf" --algo bm -j DROP
🧯 If You Can't Patch
- Isolate affected routers in separate network segment with strict firewall rules
- Replace vulnerable routers with patched or alternative models
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 1.0.0.1, device is vulnerable.Check Version:
curl -s http://router-ip/login/Auth | grep -i version or check web interfaceVerify Fix Applied:
Verify firmware version has been updated to a version later than 1.0.0.1📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /goform/SetSambaConf with long samba_userNameSda parameters
- Router crash/reboot logs
- Unusual outbound connections from router
Network Indicators:
- HTTP POST requests to router IP on port 80/443 with /goform/SetSambaConf path
- Large payloads in POST data containing samba_userNameSda parameter
SIEM Query:
source="router_logs" AND (uri_path="/goform/SetSambaConf" OR message="buffer overflow" OR message="segmentation fault")