CVE-2024-42986
📋 TL;DR
This vulnerability in Tenda FH1206 routers allows attackers to cause a Denial of Service (DoS) by sending a specially crafted POST request that triggers a stack overflow in the PPPOEPassword parameter. Attackers can crash the router, disrupting network connectivity for all connected devices. Only users running Tenda FH1206 routers with vulnerable firmware are affected.
💻 Affected Systems
- Tenda FH1206
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Router becomes completely unresponsive, requiring physical power cycle or factory reset to restore functionality, causing extended network downtime.
Likely Case
Router crashes and reboots automatically, causing temporary network interruption (1-3 minutes) until services restore.
If Mitigated
With proper network segmentation and access controls, impact is limited to isolated network segments with minimal business disruption.
🎯 Exploit Status
Exploit requires sending a POST request to the vulnerable endpoint with oversized PPPOEPassword parameter. No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Check Tenda website for firmware updates 2. Download latest firmware 3. Access router admin interface 4. Navigate to System Tools > Firmware Upgrade 5. Upload and apply new firmware 6. Reboot router
🔧 Temporary Workarounds
Disable WAN Management Access
allPrevent external access to router management interface
Access router admin > Advanced > System Tools > Remote Management > Disable
Change Default Admin Credentials
allUse strong unique credentials for router administration
Access router admin > Advanced > System Tools > Password > Set strong password
🧯 If You Can't Patch
- Place router behind firewall with strict inbound rules blocking access to management ports (typically 80, 443, 8080)
- Implement network segmentation to isolate vulnerable routers from critical systems
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Status or System Tools > Firmware UpgradeCheck Version:
curl -s http://router-ip/ | grep -i firmware || ssh admin@router-ip 'cat /proc/version'Verify Fix Applied:
Verify firmware version is newer than v02.03.01.35 and test POST requests to /goform/AdvSetWan with large PPPOEPassword parameter no longer cause crashes📡 Detection & Monitoring
Log Indicators:
- Router crash/reboot logs
- Multiple failed POST requests to /goform/AdvSetWan
- Unusual traffic patterns to router management interface
Network Indicators:
- HTTP POST requests with unusually large PPPOEPassword parameter
- Traffic to router port 80/443 from unexpected sources
- Sudden loss of router connectivity
SIEM Query:
source="router_logs" AND ("AdvSetWan" OR "PPPOEPassword") AND bytes>1000