CVE-2025-69765: Tenda AX3 Firmware RCE Vulnerability

CVE-2025-69765 Overview

A stack overflow vulnerability exists in Tenda AX3 firmware version 16.03.12.11 within the formGetIptv function. The vulnerability is triggered through improper handling of the list parameter, which can lead to memory corruption and potentially enable remote code execution. This network-accessible vulnerability requires no authentication or user interaction to exploit, making it a significant threat to affected devices.

Critical Impact

Attackers can remotely exploit this stack overflow vulnerability to corrupt memory on Tenda AX3 routers, potentially leading to device compromise, denial of service, or remote code execution without authentication.

Affected Products

• Tenda AX3 Firmware version 16.03.12.11
• Tenda AX3 Hardware Device

Discovery Timeline

• 2026-03-03 - CVE-2025-69765 published to NVD
• 2026-03-04 - Last updated in NVD database

Technical Details for CVE-2025-69765

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption issue that occurs when a program writes data beyond the boundaries of a fixed-size buffer allocated on the stack. In the context of the Tenda AX3 router, the formGetIptv function fails to properly validate the length of input received through the list parameter before copying it to a stack-allocated buffer.

When an attacker sends a specially crafted request with an oversized list parameter value, the function copies the malicious input past the designated buffer boundary. This overflow corrupts adjacent stack memory, including saved registers and the return address. By carefully crafting the overflow payload, an attacker could potentially redirect program execution to arbitrary code.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the formGetIptv function. The firmware fails to implement proper bounds checking when processing the list parameter, allowing user-controlled data to exceed the allocated buffer size on the stack. This is a common vulnerability pattern in embedded device firmware where memory-safe programming practices are not consistently applied.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker with network access to the Tenda AX3 router's web interface can exploit this vulnerability by sending a malicious HTTP request to the endpoint handling the formGetIptv function with an oversized list parameter.

The exploitation flow involves:

1. Attacker identifies a vulnerable Tenda AX3 router on the network
2. Attacker crafts a malicious HTTP request targeting the formGetIptv endpoint
3. The request includes an oversized value for the list parameter
4. The vulnerable function copies this data to a stack buffer without bounds checking
5. Stack memory is corrupted, potentially overwriting the return address
6. Upon function return, control flow may be redirected to attacker-controlled code

For detailed technical analysis, refer to the Notion Analysis of Tenda AX3.

Detection Methods for CVE-2025-69765

Indicators of Compromise

• Unexpected router reboots or crashes that may indicate exploitation attempts
• Anomalous HTTP requests to the router's web interface containing unusually long parameter values
• Modified router configurations or unauthorized administrative access
• Unusual outbound network traffic from the router indicating potential backdoor activity

Detection Strategies

• Monitor network traffic for HTTP requests to Tenda AX3 web interfaces containing abnormally long list parameter values
• Implement intrusion detection rules to flag requests to formGetIptv endpoints with payload sizes exceeding expected thresholds
• Deploy network segmentation to isolate IoT devices and monitor cross-segment traffic anomalies
• Configure logging on network perimeter devices to capture and analyze traffic to vulnerable Tenda devices

Monitoring Recommendations

• Enable verbose logging on network firewalls and IDS/IPS systems monitoring traffic to Tenda devices
• Establish baseline behavior for router communications and alert on deviations
• Monitor for firmware integrity changes that could indicate post-exploitation persistence
• Implement continuous asset discovery to identify all Tenda AX3 devices in the environment

How to Mitigate CVE-2025-69765

Immediate Actions Required

• Restrict network access to the Tenda AX3 management interface to trusted IP addresses only
• Disable remote management features if not required
• Place vulnerable devices behind a properly configured firewall that filters malicious requests
• Consider network segmentation to isolate IoT devices from critical network resources
• Monitor for vendor firmware updates that address this vulnerability

Patch Information

At the time of publication, no official patch information is available from Tenda. Organizations should monitor Tenda's official support channels for firmware updates addressing CVE-2025-69765. Until a patch is released, implementing the recommended workarounds is critical to reduce exposure to this vulnerability.

Workarounds

• Implement access control lists (ACLs) to restrict management interface access to trusted networks only
• Disable the router's web management interface from WAN-facing interfaces
• Deploy a web application firewall (WAF) rule to filter requests with oversized parameters
• Consider replacing vulnerable devices with alternative products if no patch becomes available

# Example iptables rules to restrict management access (apply on upstream firewall)
# Block external access to router management port (adjust IP and port as needed)
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 80 -j DROP
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 443 -j DROP

# Allow management access only from trusted admin network
iptables -I FORWARD -s 10.0.100.0/24 -d 192.168.1.1 -p tcp --dport 80 -j ACCEPT