CVE-2023-27239
📋 TL;DR
CVE-2023-27239 is a critical stack overflow vulnerability in Tenda AX3 routers that allows remote attackers to execute arbitrary code by sending specially crafted requests to the /goform/WifiGuestSet endpoint. This affects all users running vulnerable firmware versions of Tenda AX3 routers, potentially giving attackers full control over the device.
💻 Affected Systems
- Tenda AX3
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, persistent backdoor installation, network traffic interception, and lateral movement to connected devices.
Likely Case
Router takeover allowing attackers to modify DNS settings, intercept traffic, deploy malware to connected devices, or use the router as part of a botnet.
If Mitigated
Limited impact if the router is behind a firewall with strict inbound rules and the vulnerable service is not internet-facing.
🎯 Exploit Status
Public proof-of-concept code exists in GitHub repositories, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Tenda website for latest firmware (specific version not documented in public sources)
Vendor Advisory: Not publicly available - check Tenda support portal
Restart Required: Yes
Instructions:
1. Log into router admin interface 2. Navigate to System Tools > Firmware Upgrade 3. Download latest firmware from Tenda website 4. Upload and install firmware 5. Reboot router
🔧 Temporary Workarounds
Disable Guest WiFi
allDisable the guest WiFi feature to remove the vulnerable endpoint
Restrict WAN Access
allConfigure firewall to block external access to router management interface
🧯 If You Can't Patch
- Isolate router on separate VLAN with strict network segmentation
- Implement network monitoring for suspicious requests to /goform/WifiGuestSet endpoint
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is V16.03.12.11 or earlier, assume vulnerable.Check Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
Verify firmware version has been updated to a version after V16.03.12.11 and test that guest WiFi functionality works without crashing.📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /goform/WifiGuestSet with large shareSpeed parameter
- Router crash/reboot logs
- Unusual process execution in router logs
Network Indicators:
- HTTP POST requests to /goform/WifiGuestSet with oversized payloads
- Unusual outbound connections from router
SIEM Query:
source="router_logs" AND (uri_path="/goform/WifiGuestSet" AND content_length>1000)