CVE-2026-2137: Tenda TX3 Buffer Overflow Vulnerability

CVE-2026-2137 Overview

A buffer overflow vulnerability has been discovered in Tenda TX3 routers running firmware versions up to 16.03.13.11_multi. This vulnerability impacts the /goform/SetIpMacBind endpoint, where improper handling of the list argument allows attackers to trigger a buffer overflow condition. The vulnerability can be exploited remotely, enabling potential code execution or denial of service on affected devices. The exploit has been publicly disclosed and proof-of-concept code is available.

Critical Impact
Remote attackers can exploit this buffer overflow vulnerability in Tenda TX3 routers to potentially execute arbitrary code or cause denial of service, compromising network security infrastructure.

Affected Products

Tenda TX3 Firmware (versions up to 16.03.13.11_multi)
Tenda TX3 Hardware Device
All network configurations utilizing the affected firmware version

Discovery Timeline

2026-02-08 - CVE-2026-2137 published to NVD
2026-02-11 - Last updated in NVD database

Technical Details for CVE-2026-2137

Vulnerability Analysis

This vulnerability resides in the web management interface of Tenda TX3 routers, specifically within the /goform/SetIpMacBind function. The affected endpoint processes IP-to-MAC address binding configurations but fails to properly validate the length of the list parameter before copying it into a fixed-size buffer.

The weakness is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-120 (Buffer Copy without Checking Size of Input), indicating that the application performs buffer operations without adequate boundary checks. When an attacker supplies an oversized list argument, the resulting buffer overflow can corrupt adjacent memory regions.

Given the network attack vector and low complexity required for exploitation, this vulnerability poses significant risk to organizations deploying these devices. The vulnerability can be exploited with low privileges and requires no user interaction, making automated exploitation feasible.

Root Cause

The root cause stems from insufficient input validation in the firmware's web server component. The SetIpMacBind function accepts the list parameter from user-supplied HTTP requests and copies this data into a stack or heap buffer without verifying that the input length does not exceed the allocated buffer size. This classic buffer overflow pattern allows attackers to overwrite adjacent memory, potentially including return addresses or function pointers.

Attack Vector

The attack can be initiated remotely over the network by sending a crafted HTTP POST request to the vulnerable /goform/SetIpMacBind endpoint. An authenticated attacker with low-level privileges can exploit this vulnerability by manipulating the list parameter with an oversized payload.

The exploitation process involves:

Establishing network connectivity to the target Tenda TX3 router
Authenticating with low-privilege credentials to the web management interface
Sending a malicious HTTP request to /goform/SetIpMacBind with an oversized list parameter
The overflow corrupts memory, potentially leading to code execution or device crash

Technical details and proof-of-concept code are available in the GitHub PoC Repository maintained by security researcher MRAdera. Additional vulnerability tracking information is available through VulDB #344772.

Detection Methods for CVE-2026-2137

Indicators of Compromise

Unusual HTTP POST requests targeting /goform/SetIpMacBind with abnormally large payloads
Router crashes or unexpected reboots following web interface access
Anomalous outbound network traffic from the router indicating potential compromise
Memory corruption errors or segmentation faults in router logs

Detection Strategies

Deploy network intrusion detection signatures monitoring for oversized list parameters in requests to /goform/SetIpMacBind
Implement deep packet inspection rules to identify malformed HTTP POST requests targeting Tenda router endpoints
Configure SIEM alerts for repeated authentication attempts followed by requests to the vulnerable endpoint
Monitor for unusual patterns of router restarts or management interface unavailability

Monitoring Recommendations

Enable comprehensive logging on network firewalls monitoring traffic to router management interfaces
Implement network segmentation to isolate IoT devices and restrict management interface access
Deploy honeypot systems mimicking vulnerable Tenda routers to detect active exploitation attempts
Regularly audit router logs for suspicious activity patterns

How to Mitigate CVE-2026-2137

Immediate Actions Required

Restrict network access to the router's web management interface using firewall rules or access control lists
Disable remote administration features if not required for operations
Implement network segmentation to isolate affected routers from untrusted networks
Monitor Tenda's official channels for firmware updates addressing this vulnerability

Patch Information

At the time of publication, no official patch has been released by Tenda. Organizations should monitor the Tenda Official Site for security updates and firmware releases addressing CVE-2026-2137. Until a patch is available, implementing the recommended workarounds is critical to reduce exposure.

Workarounds

Configure firewall rules to block external access to the router's web management interface on ports 80 and 443
Implement IP-based access restrictions allowing only trusted administrator IP addresses to reach the management interface
Consider deploying a VPN solution to secure remote administration access
If possible, disable the web management interface entirely and use console-based configuration

bash

# Example: Block external access to router management interface using iptables
# Apply on upstream firewall protecting the Tenda TX3 router
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP
# Allow management access only from trusted admin subnet
iptables -I FORWARD -s <trusted_admin_subnet> -d <router_ip> -p tcp --dport 80 -j ACCEPT