CVE-2023-27042
📋 TL;DR
CVE-2023-27042 is a buffer overflow vulnerability in Tenda AX3 routers that allows remote attackers to execute arbitrary code or cause denial of service via the /goform/SetFirewallCfg endpoint. This affects users running Tenda AX3 V16.03.12.11 firmware who have the web management interface accessible. Attackers can exploit this without authentication to potentially take full control of affected routers.
💻 Affected Systems
- Tenda AX3
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete router compromise, credential theft, network pivoting, and persistent backdoor installation.
Likely Case
Router crash/reboot causing temporary network disruption, or limited code execution for reconnaissance.
If Mitigated
Denial of service only if exploit attempts are blocked but still cause crashes.
🎯 Exploit Status
Public proof-of-concept demonstrates buffer overflow via crafted HTTP POST requests. No authentication required to trigger the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not publicly available
Restart Required: No
Instructions:
Check Tenda's official website for firmware updates. If available, download the latest firmware and apply through the router's web interface under System Tools > Firmware Upgrade.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to the vulnerable web interface
Access router web interface > Advanced > System Tools > Remote Management > Disable
Restrict Management Interface Access
allLimit web interface access to trusted IP addresses only
Access router web interface > Advanced > Security > Firewall > Add rules to restrict port 80/443 access
🧯 If You Can't Patch
- Segment affected routers in isolated network zones
- Implement network-level filtering to block requests to /goform/SetFirewallCfg
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: Login > Advanced > System Tools > Firmware Upgrade. If version is V16.03.12.11, device is vulnerable.Check Version:
curl -s http://router-ip/goform/getStatus | grep version (if API accessible)Verify Fix Applied:
Verify firmware version has changed from V16.03.12.11 to a newer version after update.📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /goform/SetFirewallCfg with large payloads
- Router crash/reboot logs
- Unusual process execution in router logs
Network Indicators:
- HTTP POST requests to /goform/SetFirewallCfg with oversized data
- Sudden router unresponsiveness followed by reboot
SIEM Query:
source="router_logs" AND (uri_path="/goform/SetFirewallCfg" AND content_length>1000) OR event="crash" AND device_model="AX3"