CVE-2025-69762: Tenda AX3 Firmware RCE Vulnerability

CVE-2025-69762 Overview

A critical stack overflow vulnerability has been identified in Tenda AX3 firmware v16.03.12.11. The vulnerability exists within the formSetIptv function and can be triggered via the list parameter. Successful exploitation can cause memory corruption and enable remote code execution, allowing attackers to gain complete control over affected devices.

Critical Impact

This stack overflow vulnerability enables remote code execution without authentication, potentially allowing attackers to compromise the router and gain persistent network access.

Affected Products

• Tenda AX3 Router
• Firmware version 16.03.12.11

Discovery Timeline

• 2026-01-21 - CVE-2025-69762 published to NVD
• 2026-01-22 - Last updated in NVD database

Technical Details for CVE-2025-69762

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow). The flaw resides in the formSetIptv function within the Tenda AX3 firmware. When processing the list parameter, the function fails to properly validate the length of user-supplied input before copying it to a fixed-size stack buffer. This lack of boundary checking allows an attacker to overflow the buffer and overwrite adjacent memory on the stack, including critical control data such as the return address.

The network-accessible nature of this vulnerability means that an attacker can exploit it remotely without requiring any authentication or user interaction. By crafting a malicious HTTP request with an oversized list parameter, an attacker can corrupt stack memory and potentially redirect program execution to attacker-controlled code.

Root Cause

The root cause of this vulnerability is improper input validation in the formSetIptv function. The function accepts user-controlled data from the list parameter and copies it to a stack-allocated buffer without verifying that the input length does not exceed the buffer's capacity. This classic buffer overflow pattern allows attackers to write beyond the allocated memory region, corrupting adjacent stack frames and control flow data.

Attack Vector

The attack is network-based and can be executed remotely. An attacker sends a specially crafted HTTP request to the vulnerable formSetIptv endpoint on the Tenda AX3 router. The list parameter in this request contains a payload that exceeds the expected buffer size, triggering the stack overflow. The payload typically consists of padding to reach the return address, followed by shellcode or a ROP chain that enables arbitrary code execution with the privileges of the web server process running on the router.

The vulnerability is particularly dangerous because it requires no authentication and no user interaction, making it ideal for automated exploitation and integration into IoT botnets.

Detection Methods for CVE-2025-69762

Indicators of Compromise

• Unexpected HTTP requests to the formSetIptv endpoint with abnormally large list parameter values
• Router crashes or unexpected reboots following network activity
• Unusual outbound network connections from the router to unknown external IP addresses
• Modified router configuration or firmware without administrator action

Detection Strategies

• Monitor HTTP traffic to Tenda AX3 routers for requests containing oversized parameters to the formSetIptv endpoint
• Implement network intrusion detection rules to flag buffer overflow attack patterns targeting embedded devices
• Deploy network segmentation to isolate IoT devices and monitor traffic anomalies
• Review router logs for signs of exploitation attempts or unauthorized access

Monitoring Recommendations

• Configure network monitoring tools to alert on suspicious traffic patterns to and from Tenda AX3 devices
• Establish baseline network behavior for routers and flag deviations
• Implement deep packet inspection for HTTP requests targeting known vulnerable endpoints
• Monitor for firmware integrity changes using hash verification where supported

How to Mitigate CVE-2025-69762

Immediate Actions Required

• Restrict network access to the router's web management interface to trusted IP addresses only
• Disable remote management features if not required
• Place affected routers behind a firewall that can filter malicious requests
• Monitor for firmware updates from Tenda and apply patches as soon as available

Patch Information

At the time of publication, no official patch information is available from Tenda. Organizations should monitor Tenda's official security advisories and support channels for firmware updates addressing this vulnerability. For detailed technical analysis, refer to the Notion Security Analysis.

Workarounds

• Disable the IPTV functionality if not required, as this may prevent the vulnerable code path from being reached
• Configure firewall rules to block external access to the router's web interface on ports 80 and 443
• Implement network access control lists (ACLs) to limit which hosts can communicate with the router
• Consider replacing affected devices with alternatives that have active security support if no patch is forthcoming

# Example firewall rule to restrict access to router management interface
# Replace 192.168.1.1 with your router's IP and 192.168.1.100 with trusted admin IP
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 80 -s ! 192.168.1.100 -j DROP
iptables -A FORWARD -d 192.168.1.1 -p tcp --dport 443 -s ! 192.168.1.100 -j DROP