CVE-2025-29357
📋 TL;DR
This buffer overflow vulnerability in Tenda RX3 routers allows attackers to cause denial of service by sending specially crafted packets to the PPTP server configuration endpoint. Attackers can crash the device or potentially execute arbitrary code. Users of affected Tenda RX3 routers with vulnerable firmware versions are at risk.
💻 Affected Systems
- Tenda RX3 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, persistent backdoor installation, and lateral movement to connected networks.
Likely Case
Denial of service causing router crashes and network disruption, requiring physical reset or power cycle to restore functionality.
If Mitigated
Limited impact with proper network segmentation and firewall rules blocking unauthorized access to management interfaces.
🎯 Exploit Status
Exploitation requires sending crafted HTTP POST requests to the vulnerable endpoint. The GitHub reference contains technical details but not a complete exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Tenda website for firmware updates beyond V16.03.13.11
Vendor Advisory: Not publicly available at time of analysis
Restart Required: Yes
Instructions:
1. Visit Tenda official website 2. Download latest firmware for RX3 model 3. Log into router admin interface 4. Navigate to System Tools > Firmware Upgrade 5. Upload and apply new firmware 6. Router will reboot automatically
🔧 Temporary Workarounds
Disable PPTP Server
allDisable the vulnerable PPTP server feature if not required
Restrict Management Access
allConfigure firewall rules to restrict access to router management interface
🧯 If You Can't Patch
- Segment router management interface to isolated VLAN
- Implement network-based intrusion prevention system (IPS) rules to detect and block exploit attempts
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Status or System ToolsCheck Version:
Login to router web interface and navigate to System Status pageVerify Fix Applied:
Verify firmware version has been updated to a version later than V16.03.13.11📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /goform/SetPptpServerCfg with long parameter values
- Router crash/reboot logs
- Unusual traffic patterns to router management interface
Network Indicators:
- HTTP POST requests with abnormally long startIp or endIp parameters
- Traffic to router port 80/443 from unexpected sources
SIEM Query:
source_ip="router_ip" AND (url_path="/goform/SetPptpServerCfg" OR http_method="POST") AND (param_length>100)