CVE-2026-3679
📋 TL;DR
A stack-based buffer overflow vulnerability in Tenda FH451 routers allows remote attackers to execute arbitrary code by manipulating the mit_linktype/PPPOEPassword parameter in the formQuickIndex function. This affects Tenda FH451 routers running firmware version 1.0.0.9. Attackers can exploit this remotely without authentication.
💻 Affected Systems
- Tenda FH451
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network infiltration, and persistent backdoor installation.
Likely Case
Router takeover enabling traffic interception, credential theft, and lateral movement into connected networks.
If Mitigated
Denial of service or limited impact if network segmentation and strict access controls are implemented.
🎯 Exploit Status
Public exploit code exists, making exploitation accessible even to less skilled attackers.
🛠️ 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. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable WAN Management
allPrevent remote access to router administration interface from internet
Network Segmentation
allIsolate vulnerable routers in separate network segments
🧯 If You Can't Patch
- Replace affected routers with patched or different models
- Implement strict firewall rules blocking all external access to router management interfaces
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface. If version is 1.0.0.9, device is vulnerable.Check Version:
Check via router web interface or SSH if enabled: cat /proc/version or check admin panel system infoVerify Fix Applied:
Verify firmware version has been updated to a version later than 1.0.0.9.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/QuickIndex
- Multiple failed buffer overflow attempts in system logs
- Unexpected router reboots or configuration changes
Network Indicators:
- Unusual traffic patterns from router to external IPs
- Malformed HTTP requests to router management interface
- Port scanning targeting router management ports
SIEM Query:
source="router_logs" AND (uri="/goform/QuickIndex" OR message="buffer overflow" OR "formQuickIndex")