CVE-2023-26976
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on Tenda AC6 routers by sending a specially crafted request to the WiFi configuration interface. It affects users running Tenda AC6 routers with firmware version 15.03.05.09_multi. The stack overflow occurs when processing the ssid parameter in the form_fast_setting_wifi_set function.
💻 Affected Systems
- Tenda AC6
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete router compromise, allowing attacker to intercept traffic, modify DNS settings, install malware, or pivot to internal networks.
Likely Case
Router crash/reboot causing denial of service, or limited code execution allowing network reconnaissance and credential theft.
If Mitigated
Denial of service only if input validation prevents full exploitation, or no impact if the vulnerable interface is not accessible.
🎯 Exploit Status
Exploitation requires authentication to the router's web interface. The GitHub references contain technical details and proof-of-concept code.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda's official website for firmware updates. 2. Download the latest firmware for AC6 model. 3. Log into router web interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and install the new firmware. 6. Reboot the router.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to the vulnerable web interface
Log into router web interface > Advanced > System Tools > Remote Management > Disable
Change Default Credentials
allUse strong, unique passwords to reduce authentication risk
Log into router web interface > Advanced > System Tools > Password > Set strong password
🧯 If You Can't Patch
- Isolate the router on a separate network segment with strict firewall rules
- Implement network monitoring for unusual traffic patterns to/from the router
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in web interface: Advanced > System Tools > Firmware UpgradeCheck Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
Verify firmware version is newer than v15.03.05.09_multi📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by successful login
- Unusual POST requests to /goform/fast_setting_wifi_set with long ssid parameters
- Router crash/reboot logs
Network Indicators:
- Unusual outbound connections from router IP
- DNS hijacking patterns
- Traffic redirection
SIEM Query:
source="router.log" AND (url="/goform/fast_setting_wifi_set" OR "ssid" AND length>100)